Lunar Boom Learning

Glossary

Course reference

AI Music Glossary

Terms remain in their lesson context when their definition changes with the surrounding concept.

Showing all 686 terms.

Ablation

An experiment that removes or changes one component to measure its contribution.

In context: Chapter 4, Designing a Small Experiment

A controlled experiment that removes or changes one component to measure its contribution.

In context: Chapter 4, Debugging Model Training

ABX test

A discrimination test where an unknown item X is identified as matching reference A or B.

In context: Chapter 5, Human Listening Tests

Acoustic detail

Fine information about timbre, texture, transients, noise, and high-frequency content.

In context: Chapter 3, Hierarchical Generation

Acoustic model

A model that predicts representations carrying information about how the audio should sound.

In context: Chapter 3, Hierarchical Generation

Acoustic token

A discrete codec token that preserves information used to reconstruct sound.

In context: Chapter 3, Hierarchical Generation

Activation checkpointing

Recomputing selected forward activations during backpropagation instead of storing all of them.

In context: Chapter 4, Compute and Infrastructure

Activation memory

Memory used by intermediate forward values retained for backpropagation.

In context: Chapter 4, Compute and Infrastructure

Adam

An adaptive optimiser using moving estimates of gradients and squared gradients.

In context: Chapter 4, What Happens During Training?

AdamW

An Adam-style optimiser with weight decay separated from the gradient-based update.

In context: Chapter 4, What Happens During Training?

Adapter

A small trainable module inserted into or attached to a frozen pretrained network.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Admission control

A policy deciding whether, when, and at what priority a request may enter scheduling.

In context: Chapter 5, Turning a Model Into a Product

AI music product

A complete service that accepts user intent or source material, runs models, validates and stores outputs, and provides a controlled user experience.

In context: Chapter 5, Turning a Model Into a Product

Aliasing

Distortion that occurs when frequencies are represented above the limit allowed by the sample rate.

In context: Chapter 2, Collecting and Cleaning Audio

Aligned match

A similarity result localised to corresponding temporal or symbolic regions in two items.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Alignment

The relationship between data streams that shows which parts occur at the same time.

In context: Chapter 2, What Is a Training Example?

Allocated GPU memory

GPU memory currently occupied by live framework tensors.

In context: Chapter 4, Compute and Infrastructure

Amplitude

The strength or size of a wave or recorded signal.

In context: Chapter 1, What Is Sound?

Anchor stimulus

A deliberately selected stimulus used to establish a lower or otherwise defined point on a rating scale.

In context: Chapter 5, Human Listening Tests

Annotation bias

A skew introduced by the knowledge, vocabulary, assumptions, or instructions used during annotation.

In context: Chapter 2, Dataset Balance and Bias

Annotation confidence

A recorded estimate of how certain an annotation is.

In context: Chapter 2, Metadata and Captioning

Annotator agreement

The extent to which several annotators assign the same or compatible labels.

In context: Chapter 2, Metadata and Captioning

Anti-aliasing filter

A filter used during downsampling to reduce frequencies that cannot be represented at the new sample rate.

In context: Chapter 2, Collecting and Cleaning Audio

Architecture mismatch

A difference between checkpoint and model structures that prevents direct parameter loading or reuse.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Artist concentration

The degree to which examples or hours come from a small number of artists.

In context: Chapter 2, Dataset Balance and Bias

Artist-authorized model

A model or capability developed and used under documented permission, scope, control, compensation, attribution, and withdrawal arrangements.

In context: Chapter 5, Where AI Music Models Are Heading

Aspect list

A list of short phrases describing musical properties in a clip.

In context: Chapter 2, Metadata and Captioning

Asynchronous inference

A serving pattern where a request is accepted and queued while the result is produced and retrieved separately.

In context: Chapter 5, Turning a Model Into a Product

Attention

A mechanism that lets a model combine information from selected positions in its context.

In context: Chapter 3, Prediction as the Basic Learning Task

Attention check

A trial or interaction designed to test whether a participant follows the procedure.

In context: Chapter 5, Human Listening Tests

Attribute dropout

A training procedure that independently removes selected conditioning attributes according to configured probabilities.

In context: Chapter 4, Debugging Model Training

Attribution

Credit and source information required or provided for a work or dataset.

In context: Chapter 2, Licensing, Consent, and Provenance

Attribution record

Documentation identifying contributors, systems, sources, and transformations involved in producing an asset.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Audio artifact

An unintended audible defect introduced by recording, processing, encoding, generation, or decoding.

In context: Chapter 5, What Makes Generated Music Good?

Audio caption

A natural-language description of audible content in an audio clip.

In context: Chapter 2, Metadata and Captioning

Audio channel

One separately stored stream of audio samples.

In context: Chapter 1, What Is Sound?

Audio cleaning

The process of checking, standardising, filtering, and documenting audio before model training.

In context: Chapter 2, Collecting and Cleaning Audio

Audio conditioning

Guiding generation with features or tokens derived from a reference recording.

In context: Chapter 3, Conditioning and Control

Audio embedding

A numerical vector representing selected properties of an audio segment.

In context: Chapter 5, Automated Evaluation

Audio encoder

An encoder that turns audio into a learned representation such as an embedding.

In context: Chapter 1, Audio Embeddings

Audio fidelity

The perceived technical quality and acoustic plausibility of an audio signal.

In context: Chapter 5, What Makes Generated Music Good?

Audio fingerprint

A compact representation designed to identify the same or near-identical audio across files.

In context: Chapter 2, Collecting and Cleaning Audio

A compact representation designed to identify the same recording or excerpt despite selected distortions.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Audio stream

A sequence of encoded audio data stored inside a media container.

In context: Chapter 2, Collecting and Cleaning Audio

Audio token

A discrete ID selected from a learned codebook to represent part of a compressed audio signal.

In context: Chapter 1, Audio Tokens and Neural Codecs

A discrete symbol representing part of a learned compressed audio representation.

In context: Chapter 3, Prediction as the Basic Learning Task

Audio watermark

A signal embedded into audio so an associated detector can later detect or recover information.

In context: Chapter 5, Similarity, Memorisation, and Attribution

A signal embedded into audio so an associated detector can later identify or recover information.

In context: Chapter 5, Where AI Music Models Are Heading

Audio-text similarity

A comparison between audio and text vectors in a joint embedding space.

In context: Chapter 5, Automated Evaluation

Authority statement

A declaration explaining which rights or permissions a contributor claims to control.

In context: Chapter 2, Licensing, Consent, and Provenance

Autoencoder

A model containing an encoder that compresses data and a decoder that reconstructs it.

In context: Chapter 3, Diffusion Models

Autograd anomaly detection

A PyTorch debugging mode that adds information for tracing problematic backward operations.

In context: Chapter 4, Debugging Model Training

Automated evaluation metric

A computational procedure assigning a value to a defined property of outputs, references, conditions, or system behaviour.

In context: Chapter 5, Automated Evaluation

Automatic differentiation

A system for calculating derivatives by recording and differentiating program operations.

In context: Chapter 4, What Happens During Training?

Autoregressive generation

Generating a sequence one step at a time, with each selected token becoming context for the next prediction.

In context: Chapter 3, Prediction as the Basic Learning Task

Generating a sequence one step at a time, with each selected output becoming context for later predictions.

In context: Chapter 3, Autoregressive Music Models

Availability bias

A skew created when easily available data is treated as representative of the wider world.

In context: Chapter 2, Dataset Balance and Bias

Backpropagation

The application of reverse-mode differentiation and the chain rule through a computational graph.

In context: Chapter 4, What Happens During Training?

Backward pass

The reverse computation that calculates gradients of the loss with respect to parameters.

In context: Chapter 4, What Happens During Training?

Balanced incomplete design

A design where each participant receives part of the full test while conditions receive balanced coverage overall.

In context: Chapter 5, Human Listening Tests

Base-model retention

The degree to which an adapted model preserves capabilities of its original checkpoint.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Baseline

A simple reference method used to judge whether a more complex method adds value.

In context: Chapter 4, Designing a Small Experiment

Batch

A group of training examples processed together.

In context: Chapter 4, What Happens During Training?

Batch size

The number of examples processed together in one batch.

In context: Chapter 4, What Happens During Training?

Bidirectional context

Information available from positions before and after a generated region.

In context: Chapter 3, Conditioning and Control

Bit depth

The number of bits used to represent each audio sample, determining how many numerical levels are available.

In context: Chapter 1, What Is Sound?

Bitrate

The number of bits used or transmitted per second.

In context: Chapter 1, Audio Tokens and Neural Codecs

Blind evaluation

Evaluation where listeners do not know which model produced each sample.

In context: Chapter 4, Designing a Small Experiment

Blind test

An evaluation where listeners do not know which system or condition produced each sample.

In context: Chapter 5, Human Listening Tests

Bootstrap interval

An uncertainty interval estimated by repeatedly resampling the observed evaluation items.

In context: Chapter 5, Automated Evaluation

Bottleneck

The resource or operation that most strongly limits system performance or capacity.

In context: Chapter 4, Compute and Infrastructure

Bottleneck adapter

An adapter that projects features into a smaller dimension and then back to the model dimension.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Boundary coherence

The degree to which material joins naturally across an edge between generated regions or sections.

In context: Chapter 3, Why Long Songs Are Difficult

Boundary continuity

Perceptual and musical smoothness where generated edits meet preserved material.

In context: Chapter 5, Where AI Music Models Are Heading

Bradley-Terry model

A statistical model estimating relative item strengths from pairwise outcomes.

In context: Chapter 5, Human Listening Tests

Branching

Creating two or more continuations from the same prefix by selecting different next tokens.

In context: Chapter 3, Autoregressive Music Models

Cadence

A harmonic or melodic gesture that creates a sense of pause, closure, or continuation.

In context: Chapter 3, Why Long Songs Are Difficult

Calibration set

Known positive and negative comparison pairs used to choose or test a decision threshold.

In context: Chapter 4, Overfitting and Memorisation

Canary release

A rollout sending a small portion of production traffic to a new version.

In context: Chapter 5, Turning a Model Into a Product

Candidate-selection policy

The rule determining how many outputs are produced and which enter evaluation.

In context: Chapter 5, What Makes Generated Music Good?

The rule determining which generated candidate is presented for evaluation.

In context: Chapter 5, Human Listening Tests

Canonical label

A standard internal label used to group spelling variants, translations, or related source labels.

In context: Chapter 2, Metadata and Captioning

Capability maturity

The level of evidence that a capability works reliably for a defined task, user group, environment, and governance framework.

In context: Chapter 5, Where AI Music Models Are Heading

Caption

A natural-language description of the content of an audio clip.

In context: Chapter 2, What Is a Training Example?

Caption generation

The process of producing a natural-language description from audio, tags, metadata, or a combination of sources.

In context: Chapter 2, Metadata and Captioning

Caption grounding

The degree to which a caption is supported by the audio or trusted metadata it describes.

In context: Chapter 2, Metadata and Captioning

Cascade

A sequence of model stages where the output of one stage becomes input to the next.

In context: Chapter 3, Hierarchical Generation

A sequence of model stages where one stage's output becomes the condition for another.

In context: Chapter 3, Diffusion Models

Catalogue metadata

Record information such as artist, title, album, release date, identifier, and label.

In context: Chapter 2, Metadata and Captioning

Catastrophic forgetting

A loss of previously learned capabilities caused by training on new tasks or distributions.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Causal generation

Generation of the next output using available past and current context without requiring future input.

In context: Chapter 5, Where AI Music Models Are Heading

Causal mask

A restriction that prevents a model from attending to future token positions.

In context: Chapter 3, Autoregressive Music Models

Causal model

A sequence model that predicts from earlier information without using future tokens.

In context: Chapter 3, Autoregressive Music Models

CC0

A Creative Commons public-domain dedication tool intended to let a rights holder waive copyright and related rights to the extent legally possible.

In context: Chapter 2, Licensing, Consent, and Provenance

Channel layout

The number and arrangement of audio channels, such as mono or stereo.

In context: Chapter 2, Collecting and Cleaning Audio

Checkpoint

A saved record of model and optional training state.

In context: Chapter 4, What Happens During Training?

Checkpoint compatibility

The degree to which saved parameter tensors match a target architecture and configuration.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Checkpoint retention

A policy determining which checkpoints are preserved and for how long.

In context: Chapter 4, Compute and Infrastructure

Chord sequence

An ordered set of chord labels, often aligned with bars or time positions.

In context: Chapter 3, Conditioning and Control

Chroma feature

A representation grouping spectral energy by pitch class while normally ignoring octave.

In context: Chapter 5, Automated Evaluation

Chromagram

A time-based representation that groups musical energy into pitch classes.

In context: Chapter 3, Conditioning and Control

Chunk continuity

Consistency and smoothness across separately generated streaming segments.

In context: Chapter 5, Where AI Music Models Are Heading

Chunk seam

An audible or structural mismatch at the boundary between separately generated regions.

In context: Chapter 3, Why Long Songs Are Difficult

Chunked generation

Creating a long output as several shorter regions.

In context: Chapter 3, Why Long Songs Are Difficult

CLAP similarity

Similarity between audio and text representations produced by a CLAP-style joint embedding model.

In context: Chapter 5, What Makes Generated Music Good?

Class imbalance

A distribution where labelled classes contain substantially different numbers of examples.

In context: Chapter 2, Dataset Balance and Bias

Classifier-distribution metric

A comparison based on predicted class distributions from an audio classifier.

In context: Chapter 5, Automated Evaluation

Classifier-free guidance

A method that combines conditional and unconditional diffusion predictions to adjust condition strength.

In context: Chapter 3, Diffusion Models

Classifier-free guidance dropout

A training procedure that removes all conditions for a selected proportion of examples so conditional and unconditional behaviour can be learned.

In context: Chapter 4, Debugging Model Training

Clipping

Distortion caused when a signal exceeds the level a system can represent.

In context: Chapter 2, Collecting and Cleaning Audio

Coarse acoustic token

A token from the more important or earlier codec quantisation levels, carrying a rough acoustic representation.

In context: Chapter 3, Hierarchical Generation

Coarse-to-fine generation

A process that creates a rough or compressed representation before progressively adding detail.

In context: Chapter 3, Hierarchical Generation

Codebook

A learned collection of vectors that a quantizer can choose from.

In context: Chapter 1, Audio Tokens and Neural Codecs

A learned collection of vectors that can be selected and represented by discrete token IDs.

In context: Chapter 3, Hierarchical Generation

Codec

A system that encodes data into a compressed representation and decodes it back into a usable form.

In context: Chapter 1, Audio Tokens and Neural Codecs

Codec decoder

The part of a neural codec that converts compressed representations back into a waveform.

In context: Chapter 3, Hierarchical Generation

Codec reconstruction

Audio reconstructed from a compressed codec representation.

In context: Chapter 3, Hierarchical Generation

Cold start

Additional delay caused by provisioning a worker or loading a model before it can process a request.

In context: Chapter 5, Turning a Model Into a Product

Comparison window

The duration and temporal region used as one unit in a similarity calculation.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Composition rights

Rights and permissions connected with the underlying music and lyrics.

In context: Chapter 2, Licensing, Consent, and Provenance

Compression

Reducing the amount of data needed to represent information.

In context: Chapter 1, Audio Tokens and Neural Codecs

Compression artifact

An unwanted sound introduced or made more noticeable by compression and reconstruction.

In context: Chapter 1, Audio Tokens and Neural Codecs

Computational graph

A graph of operations and dependencies connecting inputs, parameters, intermediate values, and outputs.

In context: Chapter 4, What Happens During Training?

Compute

The numerical work performed by data preparation, model operations, gradient calculation, optimisation, and evaluation.

In context: Chapter 4, Compute and Infrastructure

Condition

A piece of guidance used by a model during generation, such as text, melody, lyrics, genre, or artist.

In context: Chapter 2, What Is a Training Example?

An input supplied to guide generation.

In context: Chapter 3, Conditioning and Control

Condition ablation

A test that removes, replaces, or shuffles a condition to measure its effect.

In context: Chapter 4, Debugging Model Training

Condition adherence

The degree to which output follows requested text, melody, harmony, timing, reference, or structural controls.

In context: Chapter 5, What Makes Generated Music Good?

Condition conflict

A situation where two or more controls encourage incompatible outputs.

In context: Chapter 3, Conditioning and Control

Conditional independence assumption

An assumption that some information is no longer needed once another conditioning variable is known.

In context: Chapter 3, Hierarchical Generation

Conditional probability

The probability of an outcome given specified context or conditions.

In context: Chapter 3, Prediction as the Basic Learning Task

Conditioning

Providing extra information that changes the probability distribution over possible outputs.

In context: Chapter 3, Prediction as the Basic Learning Task

Providing information that guides a generative model toward associated outputs.

In context: Chapter 3, Conditioning and Control

Conditioning data

Information given to a generative model to guide the output it produces.

In context: Chapter 2, What Is a Training Example?

Information such as text, melody, labels, or audio used to guide generation.

In context: Chapter 3, Prediction as the Basic Learning Task

Conditioning module

A component that converts a control input into features used by a generative model.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Conditioning pathway

The transformations connecting a control input to the model's internal prediction process.

In context: Chapter 4, Debugging Model Training

Conditioning text

Text given to a generative model to guide what it produces.

In context: Chapter 2, Metadata and Captioning

Confounding variable

An uncontrolled factor that makes it difficult to identify the cause of an observed difference.

In context: Chapter 4, Designing a Small Experiment

Content Credential

A cryptographically bound C2PA manifest containing assertions about an asset and its provenance.

In context: Chapter 5, Similarity, Memorisation, and Attribution

A cryptographically bound C2PA manifest containing assertions about an asset and its provenance.

In context: Chapter 5, Where AI Music Models Are Heading

Context

The information available to the model when it makes a prediction.

In context: Chapter 3, Prediction as the Basic Learning Task

Context drift

A gradual movement of the generated sequence away from its earlier prompt, pattern, or intended direction.

In context: Chapter 3, Autoregressive Music Models

Context length

The number of earlier tokens supplied to the model for a prediction or continuation.

In context: Chapter 4, Designing a Small Experiment

Context window

The amount of sequence information a model can process together.

In context: Chapter 2, Collecting and Cleaning Audio

The part of a sequence and conditioning information available for a prediction.

In context: Chapter 3, Prediction as the Basic Learning Task

The amount of sequence and conditioning information directly available for one prediction.

In context: Chapter 3, Autoregressive Music Models

Continuation

New sequence material generated after a supplied prompt or prefix.

In context: Chapter 3, Autoregressive Music Models

Generating new material after an existing musical prefix.

In context: Chapter 3, Conditioning and Control

Continued pretraining

Continuing a pretrained model's original or closely related objective on additional data.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Contrastive learning

A training approach that brings related examples closer in a representation space and separates unrelated examples.

In context: Chapter 1, Audio Embeddings

Contributor agreement

An agreement describing what a contributor provides, controls, permits, and promises.

In context: Chapter 2, Licensing, Consent, and Provenance

Control

The practical ability to influence a selected property of generated music.

In context: Chapter 3, Conditioning and Control

Control adherence

The degree to which generated music follows a supplied condition.

In context: Chapter 3, Conditioning and Control

Control signal

Information used to influence one or more properties of generated output.

In context: Chapter 3, Conditioning and Control

Controlled variable

A relevant factor held constant across experimental conditions.

In context: Chapter 4, Designing a Small Experiment

Controlled vocabulary

A defined list of allowed labels used to make annotations more consistent.

In context: Chapter 2, Metadata and Captioning

Cosine similarity

A method for comparing the direction of two vectors.

In context: Chapter 1, Audio Embeddings

A comparison based on the angle between numerical vectors.

In context: Chapter 5, Automated Evaluation

Cost allocation

Assignment of shared infrastructure costs to products, users, requests, or other defined groupings.

In context: Chapter 5, Turning a Model Into a Product

Counterbalancing

Distribution of stimulus positions or sequences across experimental conditions.

In context: Chapter 5, Human Listening Tests

Coverage

The extent to which a dataset includes the groups, conditions, and variations needed for an intended use.

In context: Chapter 2, Dataset Balance and Bias

Crop

A selected time range taken from a longer recording.

In context: Chapter 2, Collecting and Cleaning Audio

Cross-entropy loss

A loss function that measures how well predicted token scores match the correct target.

In context: Chapter 3, Prediction as the Basic Learning Task

A loss comparing model logits with correct discrete targets.

In context: Chapter 4, What Happens During Training?

Cross-tabulation

A table showing counts or measurements for combinations of categories.

In context: Chapter 2, Dataset Balance and Bias

Data leakage

A failure in which information outside the intended training data influences training or makes evaluation easier.

In context: Chapter 2, Collecting and Cleaning Audio

Held-out information entering training or model-selection decisions and producing optimistic evaluation.

In context: Chapter 4, Designing a Small Experiment

Use of held-out information during training or model selection in a way unavailable under intended deployment.

In context: Chapter 4, Overfitting and Memorisation

Data lineage

The chain connecting a processed item with the earlier items and activities from which it came.

In context: Chapter 2, Licensing, Consent, and Provenance

Data loader

A component that selects, batches, and supplies examples to the training loop.

In context: Chapter 4, What Happens During Training?

Data minimisation

Collecting only personal information necessary for the stated purpose.

In context: Chapter 5, Human Listening Tests

Data parallelism

Distributed training where workers process different data and combine gradient information.

In context: Chapter 4, Compute and Infrastructure

Data provenance

Information about the entities, activities, and people or systems involved in producing and changing data.

In context: Chapter 2, Licensing, Consent, and Provenance

Data replication

Generation of output matching training material under a stated representation, metric, and threshold.

In context: Chapter 4, Overfitting and Memorisation

Generation of content reproducing an identifiable portion or representation of source material.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Dataset

An organised collection of records used for training, validation, testing, or analysis.

In context: Chapter 2, What Is a Training Example?

Dataset balance

The distribution of examples across the categories and characteristics relevant to an intended use.

In context: Chapter 2, Dataset Balance and Bias

Dataset bias

A systematic skew in examples, labels, collection, or evaluation that influences learned behaviour.

In context: Chapter 2, Dataset Balance and Bias

Dataset datasheet

Structured documentation describing a dataset's motivation, composition, collection, processing, uses, and limitations.

In context: Chapter 2, Dataset Balance and Bias

Documentation describing a dataset's motivation, composition, collection, processing, uses, maintenance, and limitations.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Dataset manifest

A structured record listing dataset items, identifiers, paths, metadata, splits, and provenance.

In context: Chapter 4, Designing a Small Experiment

DDIM

A diffusion sampling formulation that supports alternative and often shorter generation paths using a model trained with a standard diffusion objective.

In context: Chapter 3, Diffusion Models

DDPM

A denoising diffusion probabilistic model based on a forward corruption process and learned reverse transitions.

In context: Chapter 3, Diffusion Models

Dead-letter queue

A queue receiving work items that exceeded their successful-processing attempts.

In context: Chapter 5, Turning a Model Into a Product

Deadlock

A state where processes wait indefinitely and no worker can make progress.

In context: Chapter 4, Debugging Model Training

Debug report

A structured record of a failure, reproduction, evidence, root cause, fix, and verification.

In context: Chapter 4, Debugging Model Training

Debugging

The controlled process of locating, explaining, and correcting unexpected system behaviour.

In context: Chapter 4, Debugging Model Training

Decision rule

A predefined rule connecting evaluation evidence to an action such as release, revision, limitation, or rejection.

In context: Chapter 5, What Makes Generated Music Good?

Decoder

The part of a codec that turns the compressed representation back into waveform audio.

In context: Chapter 1, Audio Tokens and Neural Codecs

Software that turns encoded audio into sample values that can be processed or played.

In context: Chapter 2, Collecting and Cleaning Audio

The part of a model that converts a latent or compressed representation back into an output.

In context: Chapter 3, Diffusion Models

Deduplication

Finding and removing or grouping records that contain the same or nearly the same source material.

In context: Chapter 2, Collecting and Cleaning Audio

Detection and removal, grouping, or reweighting of exact or near-duplicate examples.

In context: Chapter 4, Overfitting and Memorisation

Denoising

Estimating how a corrupted representation should change toward a cleaner and more data-like state.

In context: Chapter 3, Diffusion Models

Denoising step

One update that moves the current noisy representation toward a cleaner state.

In context: Chapter 3, Diffusion Models

Deployment alias

A mutable name pointing to an immutable model or pipeline version for a deployment purpose.

In context: Chapter 5, Turning a Model Into a Product

Detached tensor

A tensor separated from the automatic-differentiation graph so earlier operations do not receive gradients through it.

In context: Chapter 4, Debugging Model Training

Diffusion model

A generative model that learns to transform noise or a corrupted representation into structured data through iterative denoising.

In context: Chapter 3, Hierarchical Generation

A generative model trained to reverse a gradual corruption process.

In context: Chapter 3, Diffusion Models

Diffusion timestep

An index representing the current noise level in the diffusion process.

In context: Chapter 3, Diffusion Models

Digital voice replica

A digital asset or model intended to recreate the identifiable voice of a particular person.

In context: Chapter 5, Where AI Music Models Are Heading

Dimension

One position or coordinate in a vector.

In context: Chapter 1, Audio Embeddings

Dimensionality reduction

A method for representing data with fewer dimensions, often so high-dimensional embeddings can be visualised.

In context: Chapter 1, Audio Embeddings

Discrete representation

A representation built from a finite set of token or code values.

In context: Chapter 3, Hierarchical Generation

Distributed checkpoint

A checkpoint designed to save and restore state partitioned across distributed workers.

In context: Chapter 4, Compute and Infrastructure

Distributed Data Parallel

A data-parallel method where each process normally holds a model replica and synchronises gradients.

In context: Chapter 4, Compute and Infrastructure

Distributed trace

A linked record of operations performed as one request crosses services and processes.

In context: Chapter 5, Turning a Model Into a Product

Distribution coverage

The degree to which generated outputs occupy relevant regions of a target space.

In context: Chapter 5, Automated Evaluation

Distribution mismatch

A difference between the data represented by training, validation, testing, or deployment inputs.

In context: Chapter 4, Overfitting and Memorisation

Distributional metric

A measure comparing statistical representations of generated and reference collections.

In context: Chapter 5, Automated Evaluation

Diversity

Meaningful variation across valid generated outputs.

In context: Chapter 5, What Makes Generated Music Good?

Domain adaptation

Adjusting a model to data whose distribution differs from the original training domain.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Domain shift

A difference between the distributions of earlier training data and new data or use cases.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Double-blind test

A test where participants and interacting administrators are prevented from knowing stimulus identities during collection.

In context: Chapter 5, Human Listening Tests

Downmixing

Combining several audio channels into fewer channels.

In context: Chapter 2, Collecting and Cleaning Audio

Dropout

A regularisation method that randomly sets selected activations to zero during training.

In context: Chapter 4, Overfitting and Memorisation

Durable Content Credential

A provenance design combining cryptographic binding with discoverable soft bindings such as fingerprints or watermarks.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Duration conditioning

Providing desired output length or timing information to the model.

In context: Chapter 3, Conditioning and Control

Dynamic batching

Combining compatible requests arriving near one another into a larger inference batch.

In context: Chapter 5, Turning a Model Into a Product

Dynamic range

The difference between the quietest and loudest signal levels that a system can represent.

In context: Chapter 1, What Is Sound?

Early stopping

Ending training or selecting a checkpoint based on held-out performance before the final planned update.

In context: Chapter 4, Overfitting and Memorisation

Editability

The degree to which generated music can be modified or integrated into a creative workflow.

In context: Chapter 5, What Makes Generated Music Good?

Effective batch size

The total number of examples contributing to one optimiser update.

In context: Chapter 4, What Happens During Training?

The total examples contributing to one optimiser update across microbatches and workers.

In context: Chapter 4, Compute and Infrastructure

Effective context

The earlier information that meaningfully influences a current prediction.

In context: Chapter 3, Why Long Songs Are Difficult

Embedding

A numerical vector produced by a model to represent learned features of an item.

In context: Chapter 1, Audio Embeddings

Embedding distribution

The statistical arrangement of a collection of vectors in an embedding space.

In context: Chapter 5, Automated Evaluation

Embedding model

A model that maps inputs into a numerical representation space.

In context: Chapter 5, Automated Evaluation

Embedding retrieval

Searching for nearby reference items using vector representations.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Embedding space

The coordinate space in which embeddings are placed and compared.

In context: Chapter 1, Audio Embeddings

Encoder

A model or part of a model that turns input data into a learned representation.

In context: Chapter 1, Audio Embeddings

The part of a codec that turns audio into a smaller learned representation.

In context: Chapter 1, Audio Tokens and Neural Codecs

The part of a model that converts input data into a compressed representation.

In context: Chapter 3, Diffusion Models

End-to-end AI music provenance

A linked record of source assets, model and dataset versions, generation conditions, edits, approvals, and release transformations.

In context: Chapter 5, Where AI Music Models Are Heading

Ending awareness

The ability to organise the final region as a musical conclusion.

In context: Chapter 3, Why Long Songs Are Difficult

Energy trajectory

The pattern of increasing, decreasing, or changing musical intensity across a piece.

In context: Chapter 3, Why Long Songs Are Difficult

Environment lock

A recorded specification of software packages and versions required by a run.

In context: Chapter 4, Compute and Infrastructure

Epoch

One pass through the examples assigned to a training dataset or sampler.

In context: Chapter 4, What Happens During Training?

Error accumulation

A process where an unwanted generated choice changes later context and increases the chance of further unwanted choices.

In context: Chapter 3, Autoregressive Music Models

Evaluation benchmark

A standardised collection of inputs, references, procedures, metrics, and reporting rules.

In context: Chapter 5, Automated Evaluation

Evaluation bias

A problem where the test data or metric gives an incomplete or uneven picture of model performance.

In context: Chapter 2, Dataset Balance and Bias

Evaluation dimension

One separately defined aspect of model or output performance.

In context: Chapter 5, What Makes Generated Music Good?

Evaluation prompt set

A fixed collection of conditions designed to test a model's intended range and known challenges.

In context: Chapter 5, What Makes Generated Music Good?

Evaluation protocol

The complete rules governing generation, preprocessing, measurement, analysis, and reporting.

In context: Chapter 5, Automated Evaluation

Evaluation question

The precise judgement a participant is instructed to make.

In context: Chapter 5, Human Listening Tests

Evaluation rubric

A structured specification of evaluation dimensions, scales, anchors, weights, gates, and decision rules.

In context: Chapter 5, What Makes Generated Music Good?

Event token

A discrete symbol representing a musical action such as a note onset, note release, velocity, or time shift.

In context: Chapter 3, Prediction as the Basic Learning Task

Event-based representation

A sequence whose tokens describe musical changes such as note starts, endings, time movement, and velocity.

In context: Chapter 4, Designing a Small Experiment

Evidence maturity

The strength and relevance of evidence supporting a capability or deployment claim.

In context: Chapter 5, Where AI Music Models Are Heading

Exact duplicate

A record or file that is byte-for-byte identical to another.

In context: Chapter 2, Collecting and Cleaning Audio

Two dataset items identical under a chosen canonical representation or hash process.

In context: Chapter 4, Overfitting and Memorisation

Exact file match

Equality of digital files or byte sequences under a cryptographic hash.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Exact match

A generated sequence identical to a reference under a selected representation and range.

In context: Chapter 4, Overfitting and Memorisation

Excerpt-selection policy

The predefined rule identifying which region of each output enters the test.

In context: Chapter 5, Human Listening Tests

Experiment

A controlled procedure designed to test a specific hypothesis.

In context: Chapter 4, Designing a Small Experiment

Experiment configuration

A structured specification of settings used to execute a model run.

In context: Chapter 4, Compute and Infrastructure

Experiment tracking

Recording run configurations, metrics, artifacts, code, and relationships.

In context: Chapter 4, Compute and Infrastructure

Expert listener

A participant selected for relevant experience, training, or demonstrated perceptual sensitivity.

In context: Chapter 5, Human Listening Tests

Exposure bias

The mismatch between training on correct prefixes and generation from prefixes containing model-selected outputs.

In context: Chapter 3, Autoregressive Music Models

Exposure count

The number of times an example or related content contributes to training updates.

In context: Chapter 4, Overfitting and Memorisation

Failure rate

The proportion of generations that violate defined requirements.

In context: Chapter 5, What Makes Generated Music Good?

Failure symptom

An observable sign of a problem that may have several possible causes.

In context: Chapter 4, Debugging Model Training

False negative

A replicated relationship missed by the selected test.

In context: Chapter 4, Overfitting and Memorisation

A screening result that fails to identify a relevant relationship.

In context: Chapter 5, Similarity, Memorisation, and Attribution

False positive

A non-replicated pair incorrectly flagged as replication under the evaluation definition.

In context: Chapter 4, Overfitting and Memorisation

A screening result that incorrectly flags unrelated material as a match.

In context: Chapter 5, Similarity, Memorisation, and Attribution

False-positive attribute

A musical property stated in a caption even though it is not supported by the audio or trusted metadata.

In context: Chapter 2, Metadata and Captioning

Feature extraction

Using frozen pretrained representations as inputs to a newly trained head or downstream model.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Feedback bias

Systematic distortion in feedback caused by response selection, interface design, candidate filtering, or missing failures.

In context: Chapter 5, Turning a Model Into a Product

File validation

Checking that a file can be read and contains the signal and technical information expected by a pipeline.

In context: Chapter 2, Collecting and Cleaning Audio

Fine acoustic token

A token from later codec quantisation levels that refines local sound and reconstruction quality.

In context: Chapter 3, Hierarchical Generation

Fine-tuning

Additional training that adapts a pretrained model to a narrower dataset, task, or behaviour.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Finite-value check

A test confirming that a tensor contains no NaN or infinite values.

In context: Chapter 4, Debugging Model Training

Fitness for purpose

Suitability of a system or output for its defined intended use.

In context: Chapter 5, What Makes Generated Music Good?

FlashAttention

An exact attention algorithm that reduces memory traffic through tiled computation.

In context: Chapter 4, Compute and Infrastructure

Formal plan

A representation describing which sections or structural roles should occur and in which order.

In context: Chapter 3, Why Long Songs Are Difficult

Forward hook

A callback invoked around a module's forward computation for inspection or instrumentation.

In context: Chapter 4, Debugging Model Training

Forward pass

The computation that transforms inputs into model predictions.

In context: Chapter 4, What Happens During Training?

Forward process

The predefined process that gradually adds noise to clean training data.

In context: Chapter 3, Diffusion Models

Fréchet Audio Distance

A metric comparing distributions of evaluated and reference audio embeddings.

In context: Chapter 5, What Makes Generated Music Good?

A distance comparing means and covariance structures of evaluated and reference audio embeddings.

In context: Chapter 5, Automated Evaluation

Freezing

Preventing selected parameters from receiving training updates.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Frequency

The number of wave cycles completed each second, measured in hertz.

In context: Chapter 1, What Is Sound?

Full fine-tuning

Updating all or nearly all trainable parameters in a pretrained model.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Fully Sharded Data Parallel

A distributed method that shards parameters, gradients, and optimiser states across workers.

In context: Chapter 4, Compute and Infrastructure

Fusion module

A component that combines information from a new condition with the internal representation of a base model.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Gain

A change applied to the level of an audio signal.

In context: Chapter 2, Collecting and Cleaning Audio

Gaussian noise

Random numerical values drawn from a normal distribution.

In context: Chapter 3, Diffusion Models

Generalisation

The ability to perform usefully on relevant examples not used for parameter updates.

In context: Chapter 4, Overfitting and Memorisation

Generalisation gap

The difference between training performance and relevant held-out performance.

In context: Chapter 4, Overfitting and Memorisation

Generated-music quality

The degree to which generated music satisfies defined technical, musical, conditional, creative, operational, and user requirements.

In context: Chapter 5, What Makes Generated Music Good?

Generation job

A durable record representing one accepted unit of generation work.

In context: Chapter 5, Turning a Model Into a Product

Generation loop

The repeated process of predicting, selecting, appending, and predicting again.

In context: Chapter 3, Autoregressive Music Models

Generation manifest

A structured record of the model, inputs, settings, assets, transformations, and approvals associated with an output.

In context: Chapter 5, Similarity, Memorisation, and Attribution

A structured record of the inputs, model, settings, transformations, evaluations, outputs, and approvals for one generation.

In context: Chapter 5, Turning a Model Into a Product

Genre mapping

Connecting genre labels from one vocabulary or taxonomy with labels in another.

In context: Chapter 2, Metadata and Captioning

Global coherence

Consistency, development, and meaningful organisation across the complete structure of a piece.

In context: Chapter 3, Why Long Songs Are Difficult

Global condition

A condition intended to guide the generated output as a whole.

In context: Chapter 3, Conditioning and Control

Global musical coherence

Organisation and development of musical ideas across a complete piece.

In context: Chapter 5, What Makes Generated Music Good?

Global step

Golden batch

A fixed and inspected batch used as a reference across runs or code changes.

In context: Chapter 4, Debugging Model Training

GPU

A processor commonly used to accelerate parallel numerical operations in neural networks.

In context: Chapter 4, Compute and Infrastructure

GPU memory

Device memory used to store tensors and state needed by GPU operations.

In context: Chapter 4, Compute and Infrastructure

Gradient

Information showing how model parameters should change to reduce the loss.

In context: Chapter 3, Prediction as the Basic Learning Task

A collection of derivatives showing how the loss changes locally with model parameters.

In context: Chapter 4, What Happens During Training?

Gradient accumulation

Adding gradients from several batches before one optimiser update.

In context: Chapter 4, What Happens During Training?

Adding gradients from several microbatches before one optimiser update.

In context: Chapter 4, Compute and Infrastructure

Gradient clipping

Limiting gradient magnitude before an optimiser update.

In context: Chapter 4, What Happens During Training?

Limiting gradient magnitude before an optimiser update.

In context: Chapter 4, Debugging Model Training

Gradient hook

A callback invoked when a tensor gradient is calculated.

In context: Chapter 4, Debugging Model Training

Gradient memory

Memory used to store derivatives for trainable parameters.

In context: Chapter 4, Compute and Infrastructure

Gradient norm

A measurement of the overall magnitude of a collection of gradients.

In context: Chapter 4, What Happens During Training?

A measurement summarising the magnitude of a collection of gradients.

In context: Chapter 4, Debugging Model Training

Gradient scaling

Scaling the loss and gradients to reduce lower-precision numerical underflow.

In context: Chapter 4, Compute and Infrastructure

Greedy decoding

Selecting the highest-probability token at every generation step.

In context: Chapter 3, Prediction as the Basic Learning Task

Ground truth

The reference answer or observation treated as correct for a training or evaluation step.

In context: Chapter 3, Prediction as the Basic Learning Task

Ground-truth prefix

A correct earlier sequence taken from the training data.

In context: Chapter 3, Autoregressive Music Models

Group-aware evaluation

Reporting model performance separately for relevant groups rather than only as one overall score.

In context: Chapter 2, Dataset Balance and Bias

Grouped split

A split keeping all examples from the same defined group in one partition.

In context: Chapter 4, Designing a Small Experiment

Guidance scale

A generation setting controlling how strongly classifier-free guidance emphasises the condition.

In context: Chapter 3, Diffusion Models

A setting controlling how strongly a conditional prediction influences generation.

In context: Chapter 3, Conditioning and Control

Harmonic

A frequency component related to a sound's fundamental frequency that helps shape its tone.

In context: Chapter 1, Three Ways to Represent Music

Harmony conditioning

Guiding generation with chord or tonal information.

In context: Chapter 3, Conditioning and Control

Head class

A category with many training examples.

In context: Chapter 2, Dataset Balance and Bias

Hertz

The unit for cycles per second, abbreviated Hz.

In context: Chapter 1, What Is Sound?

Hidden reference

A reference-quality stimulus presented anonymously among evaluated conditions.

In context: Chapter 5, Human Listening Tests

Hierarchical generation

Generation divided into levels that operate at different representations, resolutions, or time scales.

In context: Chapter 3, Autoregressive Music Models

Generation where one representation or model stage provides guidance for a later stage at another level of detail.

In context: Chapter 3, Hierarchical Generation

Hierarchical planning

Generating or specifying high-level structure before creating lower-level musical events or audio.

In context: Chapter 3, Why Long Songs Are Difficult

Hierarchy

An arrangement of representations or models operating at different levels of compression, detail, or time scale.

In context: Chapter 3, Hierarchical Generation

Human listening test

A structured study in which participants listen to audio and provide defined judgements.

In context: Chapter 5, Human Listening Tests

Hypothesis

A specific prediction about what an experiment will show.

In context: Chapter 4, Designing a Small Experiment

Idempotency key

An identifier used to prevent repeated submissions from creating duplicate effects.

In context: Chapter 5, Turning a Model Into a Product

Identity drift

A gradual loss of the musical characteristics established earlier in a generation.

In context: Chapter 3, Why Long Songs Are Difficult

Incident response

The planned process for detecting, containing, investigating, communicating, and correcting a harmful or unreliable event.

In context: Chapter 5, Turning a Model Into a Product

Inference

Using a trained model to produce outputs without updating its learned parameters.

In context: Chapter 5, Turning a Model Into a Product

Inference latency

The time required for a trained model to produce an output.

In context: Chapter 3, Autoregressive Music Models

Inference mode

A PyTorch execution mode disabling gradient-related tracking and selected autograd overhead.

In context: Chapter 5, Turning a Model Into a Product

Inference-only use

Using a pretrained model without updating any parameters.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Ingredient

An asset or data item recorded as a component of, parent of, or input to another asset.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Initial noise

The random starting representation used during standard diffusion generation.

In context: Chapter 3, Diffusion Models

Inpainting

Generating or replacing a selected region while preserving surrounding material.

In context: Chapter 3, Conditioning and Control

Input

The information given to a model so it can make a prediction.

In context: Chapter 2, What Is a Training Example?

Intersection

A combination of two or more characteristics analysed together.

In context: Chapter 2, Dataset Balance and Bias

Intra-prompt diversity

Variation among outputs generated from the same condition.

In context: Chapter 5, What Makes Generated Music Good?

Iterative refinement

Improving a partial or uncertain representation over several repeated steps.

In context: Chapter 3, Hierarchical Generation

Improving a representation through several repeated updates.

In context: Chapter 3, Diffusion Models

Job queue

A durable waiting structure separating accepted work from available processing capacity.

In context: Chapter 5, Turning a Model Into a Product

Job state

A named stage describing the current lifecycle position of a generation job.

In context: Chapter 5, Turning a Model Into a Product

Joint embedding

A shared representation space that allows different data types, such as audio and text, to be compared.

In context: Chapter 1, Audio Embeddings

Kullback-Leibler divergence

A directional measure of how one probability distribution differs from another.

In context: Chapter 5, Automated Evaluation

Label

A category or value attached to an example and used as a target or description.

In context: Chapter 2, What Is a Training Example?

Label bias

A systematic problem in how examples are named, categorised, or annotated.

In context: Chapter 2, Dataset Balance and Bias

Label source

The person, system, catalogue, or model that produced an annotation.

In context: Chapter 2, Metadata and Captioning

Language model

A model that learns to predict sequences of tokens. In audio generation, the tokens can represent compressed sound rather than text.

In context: Chapter 1, Audio Tokens and Neural Codecs

Latent diffusion

Diffusion performed in a compressed autoencoder representation rather than the original data space.

In context: Chapter 3, Diffusion Models

Latent representation

A learned internal representation that stores useful information in a more compact form than the original input.

In context: Chapter 1, Audio Tokens and Neural Codecs

Latent space

A learned compressed numerical space produced by an encoder.

In context: Chapter 3, Diffusion Models

Layered moderation

A policy workflow using multiple checks at different stages of the generation pipeline.

In context: Chapter 5, Turning a Model Into a Product

Learning rate

A hyperparameter controlling the scale of optimiser updates.

In context: Chapter 4, What Happens During Training?

Learning-rate scheduler

A rule that changes the learning rate during training.

In context: Chapter 4, What Happens During Training?

Licence

A set of terms describing how data or content may be accessed, copied, modified, or used.

In context: Chapter 2, What Is a Training Example?

Permission that allows specified uses under stated conditions.

In context: Chapter 2, Licensing, Consent, and Provenance

Licence compatibility

Whether the permissions and conditions attached to different assets or datasets can operate together for the intended use and distribution.

In context: Chapter 2, Licensing, Consent, and Provenance

Licence condition

A requirement or limit attached to a licence.

In context: Chapter 2, Licensing, Consent, and Provenance

Licensee

A person or organisation receiving permission under a licence.

In context: Chapter 2, Licensing, Consent, and Provenance

Licensor

A person or organisation that grants permission under a licence.

In context: Chapter 2, Licensing, Consent, and Provenance

Limited deployment

A capability made available to a restricted set of users, contexts, regions, or partners.

In context: Chapter 5, Where AI Music Models Are Heading

Listener calibration

Practice and instruction used to familiarise participants with the task and scale.

In context: Chapter 5, Human Listening Tests

Listener disagreement

Variation among listeners' ratings or preferences for the same material.

In context: Chapter 5, What Makes Generated Music Good?

Variation among participants' judgements of the same stimulus or comparison.

In context: Chapter 5, Human Listening Tests

Listener fatigue

Reduced attention or changed judgement caused by prolonged listening or repeated evaluation.

In context: Chapter 5, Human Listening Tests

Listener stratum

A predefined participant subgroup analysed separately because its background may affect judgement.

In context: Chapter 5, Human Listening Tests

Local coherence

Consistency and plausibility across a relatively short span of music.

In context: Chapter 3, Why Long Songs Are Difficult

Local condition

A condition whose value or influence changes across time.

In context: Chapter 3, Conditioning and Control

Local musical coherence

Consistency among nearby rhythmic, melodic, harmonic, and timbral events.

In context: Chapter 5, What Makes Generated Music Good?

Local refinement

Adding detail using nearby context rather than remodelling the complete long sequence.

In context: Chapter 3, Hierarchical Generation

Logit

An unnormalised score produced for one possible output.

In context: Chapter 3, Prediction as the Basic Learning Task

Long-form music generation

Generation over a duration requiring persistent structure, development, transitions, and resolution.

In context: Chapter 5, Where AI Music Models Are Heading

Long-range dependency

A relationship between sequence events that are far apart.

In context: Chapter 3, Prediction as the Basic Learning Task

A meaningful relationship between sequence events separated by many tokens.

In context: Chapter 3, Autoregressive Music Models

A meaningful relationship between musical events separated by many tokens or seconds.

In context: Chapter 3, Why Long Songs Are Difficult

Long-tail distribution

A distribution with a few very common categories and many categories containing relatively few examples.

In context: Chapter 2, Dataset Balance and Bias

Long-term structure

Musical relationships that extend across relatively long spans, such as phrases, motifs, and sections.

In context: Chapter 3, Hierarchical Generation

Loop collapse

A failure mode where music becomes stuck repeating a short pattern with little development.

In context: Chapter 3, Why Long Songs Are Difficult

LoRA

A parameter-efficient method that learns low-rank updates to selected frozen weight matrices.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

LoRA rank

The inner dimension controlling the size and capacity of a LoRA update.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Loss

A numerical measure of prediction error used to guide model updates.

In context: Chapter 3, Prediction as the Basic Learning Task

Loss curve

A plot or sequence showing loss values across training progress.

In context: Chapter 4, Overfitting and Memorisation

Loss function

A function converting predictions and targets into a numerical optimisation objective.

In context: Chapter 4, What Happens During Training?

Loss reweighting

Changing how strongly errors from selected examples or groups affect the training objective.

In context: Chapter 2, Dataset Balance and Bias

Lossy compression

Compression that removes some information to produce a smaller representation.

In context: Chapter 1, Audio Tokens and Neural Codecs

Loudness matching

Adjustment of playback or file gain so stimuli have similar measured programme loudness.

In context: Chapter 5, Human Listening Tests

Loudness normalisation

Adjusting gain so measured loudness moves toward a chosen target.

In context: Chapter 2, Collecting and Cleaning Audio

Low-rank update

A matrix update represented as the product of two smaller matrices.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

LUFS

A unit commonly used to express loudness measured with an algorithm based on ITU-R BS.1770.

In context: Chapter 2, Collecting and Cleaning Audio

Lyrics

The words intended to be sung in a song.

In context: Chapter 2, What Is a Training Example?

Lyrics conditioning

Guiding vocal music generation with words intended to be sung.

In context: Chapter 3, Conditioning and Control

Mainstream drift

A tendency for an output requested in a low-resource or niche style to move toward patterns from more common styles.

In context: Chapter 2, Dataset Balance and Bias

Markov model

A probabilistic sequence model whose next prediction depends on a limited recent state history.

In context: Chapter 4, Designing a Small Experiment

Masked generation

Generation in which selected positions or regions are hidden and reconstructed from visible context and conditions.

In context: Chapter 5, Where AI Music Models Are Heading

Masked region

A selected part of a representation hidden from the model and generated or replaced.

In context: Chapter 3, Conditioning and Control

Master rights

Rights and permissions connected with a particular sound recording.

In context: Chapter 2, Licensing, Consent, and Provenance

Meaningful human control

The practical ability to understand, direct, reject, inspect, reverse, or escalate important system actions.

In context: Chapter 5, Where AI Music Models Are Heading

Measurement bias

A skew caused by using a metric or proxy that does not measure the intended concept equally well across groups.

In context: Chapter 2, Dataset Balance and Bias

Melodic similarity

Resemblance between pitch and timing patterns under a defined representation and permitted transformations.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Melody conditioning

Guiding generation with a representation of melodic pitch movement and timing.

In context: Chapter 3, Conditioning and Control

Membership inference

An attempt to determine whether a candidate example was included in model training.

In context: Chapter 4, Overfitting and Memorisation

An attempt to infer whether an item was part of a model's training data from observable behaviour.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Memorisation

Retention of information specific to one or more training examples.

In context: Chapter 4, Overfitting and Memorisation

Retention of example-specific training information that can influence or be reproduced by a model.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Metadata

Information that describes, organises, or helps analyse a record.

In context: Chapter 2, What Is a Training Example?

Information that describes, identifies, organises, or gives context to a music record.

In context: Chapter 2, Metadata and Captioning

Metric gaming

Improving a measured score without equivalent improvement in the intended real-world objective.

In context: Chapter 5, Automated Evaluation

Metric reliability

The consistency of a metric under equivalent defined conditions.

In context: Chapter 5, Automated Evaluation

Metric validity

The degree to which a metric provides evidence about its intended property and decision.

In context: Chapter 5, Automated Evaluation

Microbatch

The examples processed in one forward and backward pass on one worker.

In context: Chapter 4, Compute and Infrastructure

MIDI

A technical standard for sending and storing musical performance instructions as timed events.

In context: Chapter 1, Three Ways to Represent Music

A technical standard for representing musical performance instructions as timed events.

In context: Chapter 2, What Is a Training Example?

A protocol and file format representing musical performance messages and timing.

In context: Chapter 4, Designing a Small Experiment

MIDI event

A timed instruction such as note on, note off, program change, pitch bend, or controller movement.

In context: Chapter 1, Three Ways to Represent Music

Mini-batch

A subset of the training dataset used to estimate an update.

In context: Chapter 4, What Happens During Training?

Minimal reproduction

The smallest program or pipeline that still demonstrates a failure.

In context: Chapter 4, Debugging Model Training

Missing attribute

A relevant audible property that a caption or annotation leaves out.

In context: Chapter 2, Metadata and Captioning

Missing gradient

An expected trainable parameter has no calculated gradient after backpropagation.

In context: Chapter 4, Debugging Model Training

Mixed-precision training

Training that uses more than one numerical precision across operations.

In context: Chapter 4, What Happens During Training?

Training that uses more than one numerical precision across operations and stored values.

In context: Chapter 4, Compute and Infrastructure

Mixture consistency

Compatibility between generated stems and the combined full mix.

In context: Chapter 5, Where AI Music Models Are Heading

Mode collapse

A failure where a generator produces a narrow range of outputs relative to the intended distribution.

In context: Chapter 5, What Makes Generated Music Good?

Model capacity

The range and complexity of functions or patterns a model can represent.

In context: Chapter 4, Overfitting and Memorisation

Model card

Documentation describing a model's purpose, intended use, evaluation, limitations, risks, and context.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Model checkpoint

A persistent saved record containing model and optional training state.

In context: Chapter 4, Compute and Infrastructure

Model evaluation

One forward computation of the denoising network during sampling.

In context: Chapter 3, Diffusion Models

Model parallelism

Distributing different model components or tensor operations across devices.

In context: Chapter 4, Compute and Infrastructure

Model version

An immutable identifier for a specific deployable model artifact and associated configuration.

In context: Chapter 5, Turning a Model Into a Product

Mono

Audio represented with one channel.

In context: Chapter 1, What Is Sound?

Motif

A short recognisable musical idea that can return or develop across a piece.

In context: Chapter 3, Why Long Songs Are Difficult

Motif identity

The features that allow a motif to remain recognisable across repetitions or variations.

In context: Chapter 3, Why Long Songs Are Difficult

Motif recurrence

The return of a recognisable motif later in a piece.

In context: Chapter 3, Why Long Songs Are Difficult

MuLan similarity

Similarity between music-audio and natural-language representations produced by MuLan.

In context: Chapter 5, What Makes Generated Music Good?

Multi-label annotation

An annotation setup where one example can receive several labels at the same time.

In context: Chapter 2, Metadata and Captioning

Multi-stream tokens

Several token sequences representing related information, such as multiple neural codec codebooks.

In context: Chapter 3, Autoregressive Music Models

Multimodal music control

Conditioning music on several input types such as text, audio, image, video, or symbolic events.

In context: Chapter 5, Where AI Music Models Are Heading

Multitrack recording

A recording project in which sources are preserved on separate synchronized tracks.

In context: Chapter 5, Where AI Music Models Are Heading

MUSHRA

A controlled subjective method for assessing intermediate levels of audio quality using multiple stimuli and anchors.

In context: Chapter 5, What Makes Generated Music Good?

A multi-stimulus audio-quality method using a reference, hidden reference, and anchors.

In context: Chapter 5, Human Listening Tests

Music inpainting

Generating a selected region while conditioning on surrounding or preserved material.

In context: Chapter 5, Where AI Music Models Are Heading

Musical composition

The underlying music and any lyrics, considered separately from a particular recorded performance.

In context: Chapter 2, Licensing, Consent, and Provenance

N-gram model

A sequence model estimating the next event from the previous fixed number of events.

In context: Chapter 4, Designing a Small Experiment

NaN

A floating-point value representing an undefined or invalid numerical result.

In context: Chapter 4, Debugging Model Training

Near duplicate

Two items that differ in presentation while preserving much of the same underlying content.

In context: Chapter 4, Overfitting and Memorisation

Near-duplicate

A different file that contains the same or nearly the same source audio after changes such as re-encoding, trimming, or gain adjustment.

In context: Chapter 2, Collecting and Cleaning Audio

Nearest neighbour

An item whose embedding is among the closest to a query embedding according to a chosen similarity measure.

In context: Chapter 1, Audio Embeddings

Nearest-neighbour audit

Retrieval of the most similar training items for each generated sample under selected metrics.

In context: Chapter 4, Overfitting and Memorisation

Negative log-likelihood

A loss related to the negative logarithm of the probability assigned to the observed target.

In context: Chapter 3, Prediction as the Basic Learning Task

Negative pair

Two training examples that should not be treated as a match.

In context: Chapter 1, Audio Embeddings

Neural audio codec

An audio codec that uses neural networks to learn how to compress and reconstruct sound.

In context: Chapter 1, Audio Tokens and Neural Codecs

A learned encoder, quantiser, and decoder that compress audio into tokens and reconstruct it.

In context: Chapter 3, Hierarchical Generation

Next-event prediction

Estimating which event is likely to occur after the available context.

In context: Chapter 3, Prediction as the Basic Learning Task

No derivatives

A licence condition restricting the sharing of adapted material.

In context: Chapter 2, Licensing, Consent, and Provenance

Noise prediction

A diffusion objective where the model estimates the noise added to a clean example.

In context: Chapter 3, Diffusion Models

Noise schedule

A rule determining the amount of noise associated with each diffusion timestep.

In context: Chapter 3, Diffusion Models

Noncommercial

A licence condition limiting permission to uses that meet the licence's noncommercial definition.

In context: Chapter 2, Licensing, Consent, and Provenance

Novelty

Difference between an output and a selected comparison set under a defined representation or metric.

In context: Chapter 5, What Makes Generated Music Good?

Nyquist frequency

Half the sample rate and the highest frequency that can be represented without aliasing under ideal sampling conditions.

In context: Chapter 2, Collecting and Cleaning Audio

Object storage

Storage that manages files as objects with data, identifiers, and metadata.

In context: Chapter 5, Turning a Model Into a Product

Observability

The ability to understand system behavior through emitted telemetry such as traces, metrics, and logs.

In context: Chapter 5, Turning a Model Into a Product

Ontology

A structured set of concepts and relationships used to describe a domain.

In context: Chapter 2, Metadata and Captioning

Operational definition

A rule translating an abstract concept into an observable or calculable measure.

In context: Chapter 5, Automated Evaluation

Optimisation instability

Training behaviour characterised by erratic loss, large updates, non-finite values, or sensitivity that prevents reliable progress.

In context: Chapter 4, Debugging Model Training

Optimisation path

The chain connecting model inputs and targets to loss, gradients, optimiser state, and parameter updates.

In context: Chapter 4, Debugging Model Training

Optimiser

An algorithm that converts gradients into parameter updates.

In context: Chapter 4, What Happens During Training?

Optimiser state

Persistent values maintained by an optimiser across parameter updates.

In context: Chapter 4, Compute and Infrastructure

Order effect

A change in judgement caused by stimulus presentation position or sequence.

In context: Chapter 5, Human Listening Tests

Original hash

A cryptographic digest used to identify the exact bytes of a source file.

In context: Chapter 2, Licensing, Consent, and Provenance

Originality

The degree to which output provides a new result rather than unacceptable reproduction of existing material.

In context: Chapter 5, What Makes Generated Music Good?

Out-of-memory error

A failure caused by an allocation request exceeding the available usable memory.

In context: Chapter 4, Compute and Infrastructure

Outpainting

Extending a known recording beyond one of its existing boundaries.

In context: Chapter 3, Conditioning and Control

Overfitting

Improving on training examples without equivalent improvement on unseen examples.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

A generalisation failure where training performance improves more than relevant held-out performance.

In context: Chapter 4, Overfitting and Memorisation

Overlap

Audio content shared by two neighbouring segments.

In context: Chapter 2, Collecting and Cleaning Audio

Oversampling

Showing selected examples or groups more frequently during training.

In context: Chapter 2, Dataset Balance and Bias

Padding mask

A record showing which positions contain real audio and which positions were added as padding.

In context: Chapter 2, Collecting and Cleaning Audio

An indicator showing which sequence positions contain valid data.

In context: Chapter 4, What Happens During Training?

Pair-level metric

A measure comparing one evaluated item with one corresponding reference or condition.

In context: Chapter 5, Automated Evaluation

Paired comparison

A test where two items are compared directly on a defined criterion.

In context: Chapter 5, Human Listening Tests

Paired reference

A known target corresponding directly to an evaluated output.

In context: Chapter 5, Automated Evaluation

Pairwise diversity

Variation estimated from distances among pairs of generated outputs.

In context: Chapter 5, Automated Evaluation

Parallel decoding

Predicting or refining several token positions during the same decoding iteration.

In context: Chapter 3, Hierarchical Generation

Parameter

A trainable numerical value inside a model.

In context: Chapter 4, What Happens During Training?

Parameter memory

Memory used to store model weights and other model-state tensors.

In context: Chapter 4, Compute and Infrastructure

Parameter update

A change to the model's learned numerical parameters during training.

In context: Chapter 3, Prediction as the Basic Learning Task

A numerical change applied to trainable model parameters.

In context: Chapter 4, What Happens During Training?

Parameter-efficient fine-tuning

Adapting a pretrained model by training only a small subset or small set of added parameters.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Partial fine-tuning

Updating selected existing layers while freezing the rest of a pretrained model.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Partial match

A generated sequence matching a defined proportion or region of a reference.

In context: Chapter 4, Overfitting and Memorisation

Path dependence

A condition where earlier generated choices change the later direction and available options.

In context: Chapter 3, Autoregressive Music Models

Peak memory

The greatest amount of memory used or reserved during a measured period.

In context: Chapter 4, Compute and Infrastructure

Performer release

An agreement documenting permission from a performer for specified uses.

In context: Chapter 2, Licensing, Consent, and Provenance

Personalized music generation

Generation adapted to a user's or group's preferences, history, profile, or immediate context.

In context: Chapter 5, Where AI Music Models Are Heading

Piano roll

A grid used to display and edit notes across time and pitch.

In context: Chapter 1, Three Ways to Represent Music

A grid representation showing active pitches across discrete time positions.

In context: Chapter 4, Designing a Small Experiment

Pipeline regression

A previously working behaviour that becomes incorrect after a system change.

In context: Chapter 4, Debugging Model Training

Pitch

The perceptual quality that makes a sound seem higher or lower.

In context: Chapter 1, What Is Sound?

Policy decision

A documented result showing whether and how an asset may be used under a named policy version.

In context: Chapter 2, Licensing, Consent, and Provenance

Positive pair

Two training examples that should be treated as related, such as a music clip and its matching description.

In context: Chapter 1, Audio Embeddings

Post-processing

Transformations applied after model generation to create validated deliverable assets.

In context: Chapter 5, Turning a Model Into a Product

Practically meaningful difference

A difference large enough to matter for the intended decision.

In context: Chapter 5, Human Listening Tests

Precomputed representation

A model input calculated before training and stored for repeated use.

In context: Chapter 4, Compute and Infrastructure

Prediction

The scores or probabilities produced by a model for possible outputs.

In context: Chapter 3, Prediction as the Basic Learning Task

Preference

A listener's relative or absolute liking for an item.

In context: Chapter 5, Human Listening Tests

Preference model

A model estimating which outputs a person or population is likely to prefer.

In context: Chapter 5, Where AI Music Models Are Heading

Prefix

The sequence of tokens appearing before the position currently being predicted.

In context: Chapter 3, Autoregressive Music Models

Presigned URL

A time-limited URL granting a specific object-storage operation.

In context: Chapter 5, Turning a Model Into a Product

Pretrained model

A model whose parameters have already been trained on an earlier dataset or objective.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Pretraining

An initial training stage intended to learn broad representations or generative behaviour.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Probability distribution

A set of probabilities assigned across possible outcomes, adding up to one.

In context: Chapter 3, Prediction as the Basic Learning Task

Processing history

A record of changes applied to data, such as resampling, segmentation, cleaning, or annotation.

In context: Chapter 2, What Is a Training Example?

A record of every change applied to a source file when creating a training derivative.

In context: Chapter 2, Collecting and Cleaning Audio

Profiling

Measuring execution time, memory allocation, communication, and input-pipeline activity.

In context: Chapter 4, Compute and Infrastructure

Programme loudness

An objective estimate of perceived loudness calculated across an audio programme.

In context: Chapter 5, Human Listening Tests

Prompt

User-supplied information requesting or describing a generated result.

In context: Chapter 3, Conditioning and Control

Prompt adherence

The degree to which generated music follows the requested description or condition.

In context: Chapter 2, Dataset Balance and Bias

The extent to which generated output matches a text description.

In context: Chapter 5, What Makes Generated Music Good?

Prompt drift

A gradual movement away from the style, content, or attributes requested by the original condition.

In context: Chapter 3, Why Long Songs Are Difficult

Prompt-processing version

An immutable identifier for the rules and transformations converting user input into model conditions.

In context: Chapter 5, Turning a Model Into a Product

Provenance

Information about where data came from, how it was processed, and what permissions or restrictions apply.

In context: Chapter 2, What Is a Training Example?

Information about where a record or annotation came from and how it was created or changed.

In context: Chapter 2, Metadata and Captioning

Recorded information about the origin, history, ingredients, and transformations of an asset.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Proxy metric

A measurable quantity used as an indirect indicator of another property.

In context: Chapter 5, Automated Evaluation

Public domain

A status where copyright restrictions do not apply to a work in the relevant jurisdiction, while separate rights in related material may still need review.

In context: Chapter 2, Licensing, Consent, and Provenance

Quality gate

A mandatory condition that must be met regardless of the overall score.

In context: Chapter 5, What Makes Generated Music Good?

Quantization

The process of replacing a value with a choice from a limited set of available values.

In context: Chapter 1, Audio Tokens and Neural Codecs

Quarantine

A separate review area for records that failed validation or need a human decision.

In context: Chapter 2, Collecting and Cleaning Audio

Quarantined

Kept out of training while missing, conflicting, disputed, or uncertain evidence is reviewed.

In context: Chapter 2, Licensing, Consent, and Provenance

Random crop

A segment whose start position is selected randomly from a longer recording.

In context: Chapter 2, Collecting and Cleaning Audio

Random initialisation

Assigning initial parameter values using a randomised numerical scheme before training.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Random seed

A value used to initialise a repeatable sequence of random numbers.

In context: Chapter 3, Diffusion Models

A value used to initialise a pseudo-random process for more consistent repetition.

In context: Chapter 4, Designing a Small Experiment

Randomisation

Assignment of presentation order or condition position using a random procedure.

In context: Chapter 5, Human Listening Tests

Rating anchor

A written or audible reference defining what a score represents.

In context: Chapter 5, What Makes Generated Music Good?

A written or audible reference explaining what a score represents.

In context: Chapter 5, Human Listening Tests

Rating scale

A defined set or continuum of response values used to express a judgement.

In context: Chapter 5, Human Listening Tests

Raw audio

Audio represented directly as a sequence of sampled signal values rather than as notes or another higher-level description.

In context: Chapter 1, Three Ways to Represent Music

Real-time factor

Processing time divided by generated audio duration.

In context: Chapter 5, Where AI Music Models Are Heading

Real-time music generation

Continuous or rapidly updated generation responding within a latency suitable for live interaction.

In context: Chapter 5, Where AI Music Models Are Heading

Recency bias

A tendency for recent context to influence a prediction more strongly than distant information.

In context: Chapter 3, Why Long Songs Are Difficult

Reconstruction

The audio produced by a decoder from a compressed representation.

In context: Chapter 1, Audio Tokens and Neural Codecs

Reconstruction quality

The degree to which an output preserves a known reference signal or its perceptually important properties.

In context: Chapter 5, Automated Evaluation

Reference coverage

The proportion and types of relevant material represented in a comparison index.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Reference set

A collection of real or target examples used as a comparison distribution or benchmark.

In context: Chapter 5, What Makes Generated Music Good?

A collection representing the target distribution used for comparison.

In context: Chapter 5, Automated Evaluation

Reference-set bias

Distortion of an evaluation caused by the composition or limitations of the comparison collection.

In context: Chapter 5, Automated Evaluation

Regression test

A test designed to detect whether a previously corrected or working behaviour becomes incorrect again.

In context: Chapter 4, Debugging Model Training

Regularisation

A strategy intended to improve behaviour on unseen data rather than only minimise training error.

In context: Chapter 4, Overfitting and Memorisation

Rehearsal data

Earlier or representative examples mixed into later training to help preserve previous capabilities.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Relative attention

An attention method that represents relationships between positions using their relative distance.

In context: Chapter 3, Autoregressive Music Models

Reliability

The consistency with which a system meets defined requirements.

In context: Chapter 5, What Makes Generated Music Good?

Repeated-item reliability check

Repetition of a trial to estimate consistency in one participant's responses.

In context: Chapter 5, Human Listening Tests

Repetition with variation

The return of recognisable musical material with selected changes.

In context: Chapter 3, Why Long Songs Are Difficult

Representation

The presence and variety of a group, category, or musical characteristic within a dataset.

In context: Chapter 2, Dataset Balance and Bias

Representation bottleneck

A compressed representation that limits how much information can pass into later stages.

In context: Chapter 3, Hierarchical Generation

Reproducibility

The degree to which an experiment can be repeated using documented data, code, configuration, and randomness controls.

In context: Chapter 4, Designing a Small Experiment

The degree to which an experiment and its results can be reconstructed or repeated.

In context: Chapter 4, Compute and Infrastructure

Reproducible failure

A failure that can be triggered consistently under recorded conditions.

In context: Chapter 4, Debugging Model Training

Request contract

A versioned schema defining accepted inputs, defaults, constraints, and expected outputs.

In context: Chapter 5, Turning a Model Into a Product

Resampling

Converting a digital audio signal from one sample rate to another.

In context: Chapter 2, Collecting and Cleaning Audio

Research demonstration

An implemented method evaluated under reported experimental conditions.

In context: Chapter 5, Where AI Music Models Are Heading

Reserved GPU memory

GPU memory retained by the framework allocator for current or later tensor allocations.

In context: Chapter 4, Compute and Infrastructure

Residual vector quantisation

A quantisation method where several codebooks progressively encode the remaining representation error.

In context: Chapter 3, Hierarchical Generation

Residual vector quantization

A method that uses several codebooks in sequence so later codebooks can encode information missed by earlier ones.

In context: Chapter 1, Audio Tokens and Neural Codecs

Resumable checkpoint

A checkpoint containing enough state to continue an interrupted training run.

In context: Chapter 4, Compute and Infrastructure

Reverse process

The learned process that transforms a noisy representation toward generated data.

In context: Chapter 3, Diffusion Models

Review required

A status used when evidence exists but a policy or legal interpretation remains uncertain.

In context: Chapter 2, Licensing, Consent, and Provenance

Revocation

Withdrawal or termination of authorization for future access or use under defined conditions.

In context: Chapter 5, Where AI Music Models Are Heading

Rhythm conditioning

Guiding generation with beat, onset, groove, or drum information.

In context: Chapter 3, Conditioning and Control

Rights holder

A person or organisation that controls one or more legal rights in an asset.

In context: Chapter 2, Licensing, Consent, and Provenance

Rollback

Restoring a previously approved model or pipeline version after a failed change.

In context: Chapter 5, Turning a Model Into a Product

Root cause

The underlying mechanism that produces the observed failure.

In context: Chapter 4, Debugging Model Training

Round-trip test

A check that data can be encoded and decoded without unexpected changes.

In context: Chapter 4, Designing a Small Experiment

A test that encodes data into an intermediate representation and decodes it for comparison with the source.

In context: Chapter 4, Debugging Model Training

Run variance

Differences between experimental runs caused by random initialisation, batch order, sampling, or numerical behaviour.

In context: Chapter 4, Designing a Small Experiment

Sample

One numerical measurement of an audio signal at a particular moment.

In context: Chapter 1, What Is Sound?

Sample rate

The number of audio samples taken per second, measured in hertz.

In context: Chapter 1, What Is Sound?

The number of audio samples represented each second.

In context: Chapter 2, Collecting and Cleaning Audio

Sample-level metric

A measure calculated for one generated item.

In context: Chapter 5, Automated Evaluation

Sampler

The algorithm that converts model predictions into updates during diffusion generation.

In context: Chapter 3, Diffusion Models

Sampling

Selecting an output according to a probability distribution.

In context: Chapter 3, Prediction as the Basic Learning Task

Sampling step

One model evaluation and representation update during generation.

In context: Chapter 3, Diffusion Models

Sampling weight

A value that changes how likely a record is to be selected during training.

In context: Chapter 2, Dataset Balance and Bias

Sanity check

A small test verifying that part of the training pipeline behaves as expected.

In context: Chapter 4, Debugging Model Training

Scheduled sampling

A training approach that gradually mixes model-generated prefixes into a previously guided sequence-training process.

In context: Chapter 3, Autoregressive Music Models

Scope of use

The defined purposes, users, projects, territories, media, duration, and transformations permitted under an authorization.

In context: Chapter 5, Where AI Music Models Are Heading

Section

A region of music with a recognisable structural role or identity.

In context: Chapter 3, Why Long Songs Are Difficult

Section identity

The musical properties that make a section recognisable when it returns.

In context: Chapter 3, Why Long Songs Are Difficult

Section recurrence

The return of a recognisable section later in a piece.

In context: Chapter 3, Why Long Songs Are Difficult

Section transition

The musical passage or change connecting one structural section with another.

In context: Chapter 3, Why Long Songs Are Difficult

Seed stability

Consistency of required behaviour across random seeds for the same condition.

In context: Chapter 5, Automated Evaluation

Segmentation

Dividing a longer recording into shorter time ranges used as separate examples.

In context: Chapter 2, Collecting and Cleaning Audio

Selection bias

A skew created by the rules or practical limits used to choose which records enter a dataset.

In context: Chapter 2, Dataset Balance and Bias

Self-similarity matrix

A comparison showing how similar different time regions of one piece are to one another.

In context: Chapter 3, Why Long Songs Are Difficult

A matrix comparing representations of different time regions within one piece.

In context: Chapter 5, Automated Evaluation

Semantic alignment

Compatibility between the high-level meaning of generated audio and its condition.

In context: Chapter 5, What Makes Generated Music Good?

Semantic model

A model that predicts or processes high-level learned content tokens.

In context: Chapter 3, Hierarchical Generation

Semantic token

A learned discrete token intended to preserve relatively high-level content or long-term structure.

In context: Chapter 3, Hierarchical Generation

Sequence model

A model designed to process or generate ordered data.

In context: Chapter 3, Prediction as the Basic Learning Task

Sequence window

A fixed or bounded section of a longer token sequence used as one model input or target.

In context: Chapter 4, Designing a Small Experiment

Serial decoding

Generation where later outputs must wait for earlier outputs to be selected.

In context: Chapter 3, Autoregressive Music Models

Service-level objective

A target for a measurable aspect of service reliability or performance over a defined period.

In context: Chapter 5, Turning a Model Into a Product

Set-level metric

A measure calculated over a collection of generated or reference items.

In context: Chapter 5, Automated Evaluation

Shadow test

A test where a new version processes copied requests without controlling the user-visible response.

In context: Chapter 5, Turning a Model Into a Product

Sharding

Dividing model, optimiser, data, or checkpoint state across workers or files.

In context: Chapter 4, Compute and Infrastructure

Share alike

A licence condition requiring certain adaptations to use the same or a compatible licence.

In context: Chapter 2, Licensing, Consent, and Provenance

Short-time Fourier transform

A method that divides a signal into short sections and measures the frequency content of each section.

In context: Chapter 1, Three Ways to Represent Music

Signal-to-noise ratio

A measurement comparing the strength of the structured signal with the strength of noise.

In context: Chapter 3, Diffusion Models

Silence threshold

A level below which a frame is treated as silent by a chosen detection rule.

In context: Chapter 2, Collecting and Cleaning Audio

Similarity

A measured or perceived relationship under a specified representation and comparison rule.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Similarity metric

A function measuring resemblance between two musical or audio representations.

In context: Chapter 4, Overfitting and Memorisation

Similarity threshold

A metric value used to flag or classify a pair under an evaluation protocol.

In context: Chapter 4, Overfitting and Memorisation

Singer-identity similarity

Perceived or measured resemblance between vocal performances with respect to performer identity cues.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Single-stimulus rating

A test where one item is presented and rated without an immediate alternative.

In context: Chapter 5, Human Listening Tests

Skipped optimiser step

An update not applied because the system detected invalid gradients or another update condition.

In context: Chapter 4, Debugging Model Training

Sliding window

A strategy that moves a fixed-size context across a longer sequence.

In context: Chapter 3, Autoregressive Music Models

Small experiment

A limited study designed to answer one important question with modest data, compute, and implementation complexity.

In context: Chapter 4, Designing a Small Experiment

Softmax

A function that converts logits into a probability distribution.

In context: Chapter 3, Prediction as the Basic Learning Task

Song form

The large-scale arrangement of musical sections across a piece.

In context: Chapter 3, Why Long Songs Are Difficult

Sound recording

A fixation of a series of sounds, such as a particular recorded performance.

In context: Chapter 2, Licensing, Consent, and Provenance

Sound wave

A travelling pattern of pressure changes moving through a medium such as air or water.

In context: Chapter 1, What Is Sound?

Source asset

The original or upstream file from which a dataset record or derivative was created.

In context: Chapter 2, Licensing, Consent, and Provenance

Source bias

A skew caused by relying heavily on particular platforms, archives, labels, or contributors.

In context: Chapter 2, Dataset Balance and Bias

Source concentration

The degree to which a dataset depends on a small number of platforms, archives, or catalogues.

In context: Chapter 2, Dataset Balance and Bias

Source label

The original label exactly as it appeared in the source data.

In context: Chapter 2, Metadata and Captioning

Source leakage

Unwanted presence of one source within another separated or generated stem.

In context: Chapter 5, Where AI Music Models Are Heading

Source-specific similarity

Resemblance involving features sufficiently specific to connect an output with an identifiable reference.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Speaker embedding

A vector representation trained to capture voice characteristics useful for distinguishing speakers.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Speaker verification

Testing whether a recording is consistent with a claimed speaker identity.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Spectral distance

A difference calculated between time-frequency representations of two audio signals.

In context: Chapter 5, Automated Evaluation

Spectrogram

A representation that shows how a signal's frequency content changes over time.

In context: Chapter 1, Three Ways to Represent Music

Spectrogram-space diffusion

Applying diffusion to a time-frequency representation of audio.

In context: Chapter 3, Diffusion Models

Stage error propagation

A process where a problem in an earlier stage affects the inputs and outputs of later stages.

In context: Chapter 3, Hierarchical Generation

Stem

An isolated or grouped component of a multitrack mix.

In context: Chapter 5, Where AI Music Models Are Heading

Stem-aware generation

Generation that represents and controls multiple musical sources separately.

In context: Chapter 5, Where AI Music Models Are Heading

Stereo

Audio represented with two channels, conventionally left and right.

In context: Chapter 1, What Is Sound?

Stochastic gradient descent

An optimiser family using gradients estimated from individual examples or mini-batches.

In context: Chapter 4, What Happens During Training?

Stopping criterion

A predefined condition that ends or pauses an experiment.

In context: Chapter 4, Designing a Small Experiment

Stopping rule

A condition that ends generation, such as a stop token, duration, or maximum sequence length.

In context: Chapter 3, Autoregressive Music Models

Storage lifecycle

Rules governing how stored objects transition, expire, or remain under retention.

In context: Chapter 5, Turning a Model Into a Product

Storage tier

A storage category selected according to speed, durability, and access requirements.

In context: Chapter 4, Compute and Infrastructure

Structural conditioning

Control information specifying musical form, sections, lyrics, chords, or other large-scale organisation.

In context: Chapter 5, Where AI Music Models Are Heading

Structure condition

A representation of form, phrases, sections, or relationships used to guide lower-level generation.

In context: Chapter 3, Why Long Songs Are Difficult

Structure graph

A graph connecting musical regions through relationships such as repetition, variation, or development.

In context: Chapter 3, Why Long Songs Are Difficult

Structured memory

A mechanism preserving or retrieving earlier information according to musical roles.

In context: Chapter 3, Why Long Songs Are Difficult

Style conditioning

Using a reference signal to guide broad musical or acoustic characteristics while generating new content.

In context: Chapter 3, Conditioning and Control

Style similarity

Resemblance in broad musical or production characteristics shared across a category or body of work.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Subjective evaluation

Measurement based on reported human perception, opinion, or preference.

In context: Chapter 5, Human Listening Tests

Success criterion

A predefined condition used to determine whether an experiment achieved its objective.

In context: Chapter 4, Designing a Small Experiment

Super-resolution

Increasing the detail or resolution of an existing representation.

In context: Chapter 3, Hierarchical Generation

Symbolic music representation

A representation of musical events and instructions rather than recorded audio samples.

In context: Chapter 4, Designing a Small Experiment

Synthesizer

A hardware or software instrument that creates sound and can respond to MIDI instructions.

In context: Chapter 1, Three Ways to Represent Music

Synthetic caption

A caption generated automatically by a model rather than written directly by a human annotator.

In context: Chapter 2, Metadata and Captioning

System-level metric

A measure of behaviour across repeated requests, prompts, failures, or operating conditions.

In context: Chapter 5, Automated Evaluation

Tag

A short descriptive label such as piano, jazz, speech, or percussion.

In context: Chapter 2, What Is a Training Example?

A short label used to describe or categorise one property of a recording.

In context: Chapter 2, Metadata and Captioning

Tail class

A category with relatively few training examples.

In context: Chapter 2, Dataset Balance and Bias

Tail latency

Latency experienced by the slowest portion of requests, commonly represented by a high percentile.

In context: Chapter 5, Turning a Model Into a Product

Target

The expected result that a model is trained to predict.

In context: Chapter 2, What Is a Training Example?

The correct output from the training data that the model is asked to predict.

In context: Chapter 3, Prediction as the Basic Learning Task

Target distribution

The desired mix of examples or training exposure chosen for a model's intended use.

In context: Chapter 2, Dataset Balance and Bias

Taxonomy

An organised system of categories and relationships used to classify items.

In context: Chapter 2, Metadata and Captioning

Teacher forcing

Training a sequence model with the correct earlier tokens from the dataset.

In context: Chapter 3, Autoregressive Music Models

Temperature

A generation setting that makes a sampling distribution more concentrated or flatter.

In context: Chapter 3, Prediction as the Basic Learning Task

Tempo conditioning

Guiding generation with a target pace, commonly represented in beats per minute.

In context: Chapter 3, Conditioning and Control

Tempo stability

Consistency of estimated rhythmic pace across a piece.

In context: Chapter 5, Automated Evaluation

Temporal alignment

A mapping between a condition and the times or sequence positions where it applies.

In context: Chapter 3, Conditioning and Control

Temporal quantisation

Mapping event times onto a fixed rhythmic grid or finite timing vocabulary.

In context: Chapter 4, Designing a Small Experiment

Test set

Held-out data reserved for final evaluation after model choices are complete.

In context: Chapter 4, Designing a Small Experiment

Text conditioning

Guiding generation with a numerical representation of written language.

In context: Chapter 3, Conditioning and Control

Text encoder

An encoder that turns text into a learned representation such as an embedding.

In context: Chapter 1, Audio Embeddings

Text-to-music generation

The task of generating music that follows a written description.

In context: Chapter 2, What Is a Training Example?

The task of generating music that follows a written description.

In context: Chapter 2, Metadata and Captioning

Timbre

The sound quality that helps distinguish two instruments or voices even when they play the same pitch.

In context: Chapter 1, Three Ways to Represent Music

Timestamp

A value marking when an event begins, ends, or occurs within a recording.

In context: Chapter 2, What Is a Training Example?

Timestep embedding

A numerical representation that tells the model which diffusion noise level it is processing.

In context: Chapter 3, Diffusion Models

Timing embedding

A numerical representation of timing information supplied as a model condition.

In context: Chapter 3, Conditioning and Control

Timing resolution

The smallest timing interval represented by a symbolic encoding.

In context: Chapter 4, Designing a Small Experiment

Tiny-batch overfit test

Repeated training on a small fixed dataset to verify that the pipeline can reduce its training error.

In context: Chapter 4, Debugging Model Training

Token

One discrete unit in the sequence processed or generated by a model.

In context: Chapter 3, Prediction as the Basic Learning Task

Token interleaving pattern

A rule for arranging tokens from several streams into an autoregressive prediction order.

In context: Chapter 3, Autoregressive Music Models

Token rate

The number of tokens represented or generated per second of audio or sequence time.

In context: Chapter 3, Autoregressive Music Models

The number of model tokens associated with one unit of audio time.

In context: Chapter 4, Compute and Infrastructure

Token stream

A sequence of token IDs ordered over time.

In context: Chapter 1, Audio Tokens and Neural Codecs

Tonal stability

Consistency or intentional evolution of pitch-class and tonal information over time.

In context: Chapter 5, Automated Evaluation

Top share

The fraction of examples or hours contributed by the largest artist, source, or category.

In context: Chapter 2, Dataset Balance and Bias

Top-k sampling

Sampling only from a fixed number of the highest-scoring token candidates.

In context: Chapter 3, Prediction as the Basic Learning Task

Top-p sampling

Sampling from the smallest set of tokens whose combined probability reaches a chosen threshold.

In context: Chapter 3, Prediction as the Basic Learning Task

Train-generation mismatch

A difference between the sequence histories or conditions used during training and free generation.

In context: Chapter 4, Debugging Model Training

Trainable parameter count

The number of parameters that receive gradients and optimiser updates.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Training

The process of adjusting model parameters to reduce a chosen loss across training examples.

In context: Chapter 4, What Happens During Training?

Training budget

A predefined limit on updates, compute, time, data exposure, or resources.

In context: Chapter 4, Designing a Small Experiment

Training example

One structured record presented to a model during training.

In context: Chapter 2, What Is a Training Example?

Training from scratch

Training relevant model parameters from random or newly constructed initial values.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Training infrastructure

The hardware, storage, network, software, scheduling, and tracking systems used to run model experiments.

In context: Chapter 4, Compute and Infrastructure

Training loss

Loss calculated on examples used in the optimisation process.

In context: Chapter 4, Overfitting and Memorisation

Training manifest

A versioned record identifying the examples or source groups used in a model-training run.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Training set

Data used to calculate losses and update model parameters.

In context: Chapter 4, Designing a Small Experiment

Training step

One batch iteration that usually includes one optimiser update.

In context: Chapter 4, What Happens During Training?

Training throughput

The amount of training work completed per unit of time.

In context: Chapter 4, Compute and Infrastructure

Training-data extraction

Generation or recovery of recognisable training examples from a trained model.

In context: Chapter 4, Overfitting and Memorisation

Elicitation of model output that reproduces identifiable training information.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Training-set membership

Whether a particular item was included in data used to update model parameters.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Transfer learning

Reusing features learned by a pretrained model for a new task.

In context: Chapter 1, Audio Embeddings

Reusing knowledge from a pretrained model for a new task, dataset, or domain.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning

Transformation log

A record of processing steps such as decoding, resampling, segmentation, annotation, and filtering.

In context: Chapter 2, Licensing, Consent, and Provenance

Transposition invariance

A comparison property that treats a melody shifted uniformly in pitch as equivalent or similar.

In context: Chapter 5, Similarity, Memorisation, and Attribution

True peak

An estimate of the highest signal peak, including peaks that may occur between stored samples.

In context: Chapter 2, Collecting and Cleaning Audio

True-peak level

An estimate of the maximum level of the reconstructed continuous audio signal.

In context: Chapter 5, Human Listening Tests

UMAP

A dimensionality reduction method often used to display high-dimensional data in two or three dimensions.

In context: Chapter 1, Audio Embeddings

Unaligned lyrics

Lyrics supplied without exact timing for each word, syllable, or phoneme.

In context: Chapter 3, Conditioning and Control

Underfitting

Failure to model important patterns even in the training data or target domain.

In context: Chapter 4, Overfitting and Memorisation

Underrepresentation

A condition where a relevant group or combination appears too rarely or narrowly for the intended use.

In context: Chapter 2, Dataset Balance and Bias

Undersampling

Reducing how often common examples or groups are used during training.

In context: Chapter 2, Dataset Balance and Bias

Unit economics

Measurement of cost and value per defined product unit.

In context: Chapter 5, Turning a Model Into a Product

Unsupported label

A label or claim that cannot be justified by the audio, trusted metadata, or another documented source.

In context: Chapter 2, Metadata and Captioning

Upsampling model

A model that predicts a denser or more detailed representation from a coarser one.

In context: Chapter 3, Hierarchical Generation

Usefulness

The degree to which a result helps a defined user complete an intended task.

In context: Chapter 5, What Makes Generated Music Good?

Valid-output rate

The proportion of generation attempts satisfying predefined technical output requirements.

In context: Chapter 5, Automated Evaluation

The proportion of generation attempts producing outputs that satisfy defined technical requirements.

In context: Chapter 5, Turning a Model Into a Product

Validation failure

A validation design or process that does not reliably estimate intended generalisation performance.

In context: Chapter 4, Overfitting and Memorisation

Validation loss

Loss calculated on held-out validation data without parameter updates.

In context: Chapter 4, Overfitting and Memorisation

Validation overfitting

Indirect adaptation to validation examples through repeated experiment decisions.

In context: Chapter 4, Overfitting and Memorisation

Validation pass

Evaluation on held-out data without parameter updates.

In context: Chapter 4, What Happens During Training?

Validation set

Held-out data used for model selection and experiment decisions without parameter updates.

In context: Chapter 4, Designing a Small Experiment

Variation

A new version that preserves selected properties of existing music while changing others.

In context: Chapter 3, Conditioning and Control

Vector

An ordered list of numbers. In an embedding, the numbers act as coordinates in a learned space.

In context: Chapter 1, Audio Embeddings

Vector quantization

A method that replaces a continuous vector with a selected vector from a codebook.

In context: Chapter 1, Audio Tokens and Neural Codecs

Velocity

A MIDI value commonly used to represent how strongly a note was played.

In context: Chapter 1, Three Ways to Represent Music

Visibility timeout

The period during which a queue message is hidden after one worker receives it.

In context: Chapter 5, Turning a Model Into a Product

Vocabulary

The complete set of token types the model can predict.

In context: Chapter 3, Prediction as the Basic Learning Task

Vocoder

A model that converts an acoustic representation such as a mel-spectrogram into a waveform.

In context: Chapter 3, Diffusion Models

VQ-VAE

A vector-quantised variational autoencoder that learns discrete latent codes and a decoder.

In context: Chapter 3, Hierarchical Generation

Warm model instance

A serving process with required model artifacts already loaded and ready for inference.

In context: Chapter 5, Turning a Model Into a Product

Watermark robustness

The degree to which a watermark remains detectable after defined transformations or attacks.

In context: Chapter 5, Similarity, Memorisation, and Attribution

Waveform

A representation of how an audio signal changes over time.

In context: Chapter 1, Three Ways to Represent Music

Waveform-space diffusion

Applying diffusion directly to time-domain audio sample values.

In context: Chapter 3, Diffusion Models

Weak label

A label that says an event appears somewhere in a clip without giving its exact timing.

In context: Chapter 2, What Is a Training Example?

A label stating that a property occurs somewhere in a clip without giving its exact time.

In context: Chapter 2, Metadata and Captioning

Weight decay

An optimisation regulariser that discourages large parameter values through a decay term or decoupled update.

In context: Chapter 4, Overfitting and Memorisation

Weighted quality score

A composite score combining dimensions according to predefined importance weights.

In context: Chapter 5, What Makes Generated Music Good?

Weights-only checkpoint

A checkpoint containing model parameters without the complete optimisation state.

In context: Chapter 4, Compute and Infrastructure

Whole-song evaluation

Assessment that examines the complete generated timeline rather than isolated excerpts.

In context: Chapter 3, Why Long Songs Are Difficult

Windowed alignment

Condition alignment calculated separately over several time regions.

In context: Chapter 5, Automated Evaluation

Withdrawal

An action ending or changing future reliance on a consent or permission under the applicable agreement or legal framework.

In context: Chapter 2, Licensing, Consent, and Provenance

Workflow evaluation

Evaluation of how a person and system complete a task rather than evaluation of one isolated output.

In context: Chapter 5, Where AI Music Models Are Heading

Zero gradient

A calculated gradient whose values are zero or effectively negligible.

In context: Chapter 4, Debugging Model Training

Zero-shot classification

Classifying an item using new text labels or descriptions without training a separate classifier on labelled examples for every class.

In context: Chapter 1, Audio Embeddings

Zero-shot use

Applying a pretrained model to a task or input without task-specific parameter training.

In context: Chapter 4, Training From Scratch Versus Fine-Tuning