Glossary - Sensing Sound and Music

This page collects the technical vocabulary of the book in one place, as a lookup list for revision and exam preparation. Every term is explained in context in the chapters, so treat these short definitions as reminders rather than as first introductions.

Absolute pitch: The ability to name or produce a specific pitch without hearing a reference tone first.
Acousmatic listening: Listening to sound separated from its visible source, typically over loudspeakers, which directs attention to the qualities of the sound itself.
Acoustics: The science of how sound is produced, transmitted, and received; the word also refers to the sonic qualities of a room.
Action–perception loop: The continuous cycle in which movement shapes what we perceive and perception shapes the next movement, central to embodied accounts of music.
Action–sound coupling: The lawful, mechanical link between an action and the sound it produces on an acoustic instrument, which listeners internalise through experience.
Action–sound mapping: The designed relation between action and sound in an electronic instrument, which can be arbitrary and reprogrammed, unlike a mechanical coupling.
ADSR envelope: A four-stage description of how a sound’s level unfolds through attack, decay, sustain, and release, widely used in synthesisers.
Affordance: What an object or environment invites a person to do, applied to sound when a heard event signals possible actions.
Aliasing: The distortion that arises when a signal contains frequencies above half the sampling rate, folding them down into false lower frequencies.
Ambisonics: A recording and reproduction technique that captures the whole sound field so it can be rotated and decoded to different loudspeaker layouts.
Amplitude: The maximum displacement of a vibrating medium from its resting position, related to the perceived loudness of a sound.
Arousal: The dimension of emotion running from calm to activated, one axis of the valence–arousal model.
Auditory scene analysis: The process by which the auditory system sorts a single incoming pressure wave into separate sound sources and streams.
Autonomic nervous system: The involuntary control system of the body whose sympathetic and parasympathetic branches regulate arousal and recovery.
Beat: The basic pulse listeners tap along to, typically most comfortable at intervals of roughly half a second; also called the tactus.
Binaural audio: Headphone reproduction that delivers to each eardrum the signal it would receive in the recorded space, using dummy-head recording or HRTF filtering.
Bit depth: The number of bits used to store each sample of a digital signal, which sets the amplitude precision and the available dynamic range.
Chills: Brief, intense responses to music with shivers and goosebumps, also called frisson, accompanied by measurable changes in skin conductance and heart activity.
Chromagram: A representation showing the energy in each of the twelve pitch classes over time, with octave information discarded, useful for analysing harmony.
Cochlea: The spiral, fluid-filled organ of the inner ear where hair cells convert mechanical vibration into nerve impulses, organised by frequency.
Cocktail party effect: The ability to focus on one voice among many competing sounds, combining spatial hearing with selective attention.
Communicative gestures: Performer movements directed at other musicians or the audience, such as cueing an entrance, one category in the taxonomy of music-related body motion.
Consonance and dissonance: The perceived stability or tension of simultaneous pitches, shaped both by the auditory system and by cultural exposure.
Continuity illusion: Hearing a tone as continuing through an interrupting noise burst, because the auditory system reconstructs what the noise plausibly masked.
Critical band: A frequency region within which the ear analyses sound as a unit, so that components falling in the same band interact and mask each other strongly.
Cross-modal correspondence: A systematic association between the senses shared by most people, such as linking high pitch with brightness or small size.
Cross-rhythm: The overlap of rhythmic streams whose periodicities do not fit into each other as whole numbers, such as three against two, creating metrical ambiguity.
Decibel: A logarithmic unit for expressing the ratio between two sound levels, matching the ear’s compressive response to intensity.
Dynamic attending: The theory that metre is a behaviour of attention, with expectancy peaking periodically so that events on strong positions become more salient.
Electrocardiography (ECG): Recording the electrical activity of the heart through electrodes on the skin, the standard method for precise beat-to-beat cardiac timing.
Electrodermal activity (EDA): Measurement of the skin’s electrical conductance, which tracks sweat-gland activity and serves as an index of sympathetic arousal.
Electroencephalography (EEG): Recording the summed electrical activity of the brain from the scalp, with excellent temporal resolution but limited spatial precision.
Electromyography (EMG): Recording the electrical activation of muscles through surface electrodes, capturing effort and tension even when little movement is visible.
Embodied music cognition: The view that musical meaning arises through the whole body’s engagement with sound rather than through listening as a purely mental act.
Enculturation: The gradual, implicit learning of the norms of surrounding music, which makes familiar rhythms and tonal hierarchies feel natural.
Entrainment: The synchronisation of one rhythmic system with another, as when movements, heartbeats, or breathing align with a musical pulse.
Envelope: The overall shape of a sound’s amplitude over time, from its onset to its decay, an important cue for timbre.
Equal-loudness contours: Curves showing the sound pressure level needed at each frequency for tones to sound equally loud, with hearing most sensitive around 2–5 kHz.
Event-related potential (ERP): An EEG pattern time-locked to a specific stimulus, used to study auditory attention, expectation, and memory.
Eye tracking: Measuring where the eyes are directed over time, used to study visual attention during score reading, performance, and multimedia.
Fixation: A pause of the gaze on one location, typically a few hundred milliseconds, during which detailed visual processing takes place.
Formant: A resonance peak of the vocal tract that amplifies some harmonics of the voice, with the lowest two formants distinguishing the vowels.
Four levels of description: The book’s organising framework of physical, digital, perceptual, and interpretive levels, used to locate whether a claim is about the air, the file, the ear, or the listener.
Fourier transform: The mathematical operation that decomposes a complex signal into sinusoids, converting the time-domain view into a frequency-domain view.
Frequency: The number of vibration cycles per second, measured in hertz, the physical counterpart of perceived pitch.
Functional magnetic resonance imaging (fMRI): Brain imaging that tracks activity indirectly through blood oxygenation, giving fine spatial detail but slow temporal resolution and a noisy scanner environment.
Functional near-infrared spectroscopy (fNIRS): An optical method measuring blood oxygenation in the cortex, silent and tolerant of movement, and therefore usable with infants and performing musicians.
Fundamental frequency: The lowest frequency component of a periodic tone, which normally determines the perceived pitch.
Gestalt principles: Perceptual grouping rules such as proximity, similarity, and continuity, by which listeners organise sounds into coherent lines and phrases.
Groove: A repeated rhythmic pattern that establishes a clear beat, and equally the pleasurable urge to move that such patterns induce.
Harmonics: Frequency components at whole-number multiples of the fundamental, whose relative strengths shape the timbre of a tone.
Head-related transfer function (HRTF): The filtering that the head, torso, and outer ear impose on incoming sound, individual to each person and essential for judging elevation and front–back position.
Hearing: The physiological detection of sound waves by the auditory system, contrasted in this book with listening as an active, interpretive process.
Heart rate variability (HRV): The variation in the intervals between successive heartbeats, with higher variability indicating relaxed, parasympathetic states.
Interaural level difference: The loudness difference between the two ears caused by the shadowing of the head, a localisation cue that works best at high frequencies.
Interaural time difference: The tiny difference in arrival time of a sound at the two ears, the main cue for left–right localisation at low frequencies.
Interdisciplinarity: Genuinely integrating theories and methods from several disciplines, rather than only placing them side by side.
Inter-onset interval: The time between the starts of successive sounds, the basic measurement unit in studies of rhythm and timing.
Just noticeable difference: The smallest change in a stimulus that a listener can reliably detect, such as about one decibel of level or a fraction of a percent of frequency.
Keynote sound: In soundscape studies, a background sound so fundamental to a place that it is mostly heard unconsciously, such as distant traffic.
Kinematics: The description of motion itself, covering position, velocity, and acceleration, without reference to the forces involved.
Kinetics: The study of the forces and torques that cause motion, which must be measured with force sensors or inferred, since cameras cannot see them.
Listening: The active, attentive interpretation of sound, as opposed to the passive registration of hearing.
Loudness: The subjective impression of a sound’s strength, which depends on frequency and context and therefore does not map directly onto sound pressure level.
Masking: One sound making another harder or impossible to hear, whether simultaneously or just before or after it, a principle exploited by perceptual audio codecs.
McGurk effect: An illusion in which seen lip movements change which speech sound is heard, demonstrating that vision participates in speech perception.
Mel-frequency cepstral coefficients (MFCCs): A compact numerical description of timbre based on a perceptually spaced frequency scale, long a standard feature in speech and music classification.
Metre: A hierarchical framework of nested pulse levels, from fast subdivisions through the beat to bar-length groupings, against which rhythms are heard.
Micromotion: The tiny involuntary movements, at millimetre scale, that remain when a person tries to stand completely still, measurable with motion capture.
MIDI: A protocol and file format that stores performance instructions such as pitch, velocity, and duration rather than recorded sound.
Mirror neurons: Neurons reported to fire both when performing an action and when observing it, often invoked, though still debated, as a basis for understanding others’ sound-producing actions.
Missing fundamental: The phenomenon of hearing a pitch at an absent fundamental frequency inferred from the spacing of its harmonics, evidence that pitch is constructed by the auditory system.
Motion capture: Any systematic recording of body movement over time, from marker-based infrared camera systems to wearable inertial sensors and video-based pose estimation.
Motiongram: A visualisation that compresses the motion in a video into a single image over time, allowing movement to be read somewhat like a spectrogram.
Music information retrieval (MIR): The research field concerned with extracting structured information from musical audio and related data, from beat tracking to recommendation.
Musicking: Small’s term for music understood as an activity that includes performing, dancing, listening, and organising, rather than as an object.
Musique concrète: Schaeffer’s compositional practice of shaping recorded sounds directly, treating environmental and instrumental recordings as raw material.
Neuroplasticity: The brain’s capacity to reorganise its connections through experience, evident in the effects of musical training.
Nyquist frequency: Half the sampling rate, the highest frequency a digital system can represent without aliasing.
Onset: The beginning of a sound event; the physically measurable start can differ from the moment a listener perceives the sound as beginning.
Organology: The academic study and classification of musical instruments, with the Hornbostel–Sachs system as the best-known scheme.
Parasympathetic nervous system: The calming branch of the autonomic nervous system, dominant during rest and relaxing music, and reflected in higher heart rate variability.
Perceived and induced emotion: The distinction between recognising the emotion a piece of music expresses and actually feeling an emotion oneself, which any study of musical emotion must specify.
Pitch: The perceived height of a tone, closely related to fundamental frequency but produced by the auditory system rather than read directly from the signal.
Pitch class: The set of all pitches that are whole octaves apart, such as every C on a keyboard, the basis of the chromagram.
Precedence effect: The dominance of the first-arriving wavefront in determining a sound’s perceived direction, which keeps room reflections from confusing localisation.
Psychoacoustics: The study of how physical sound relates to what listeners actually perceive, covering loudness, pitch, timbre, and spatial hearing.
Pupillometry: Measuring changes in pupil diameter as an index of arousal, attention, and mental effort, with careful control of lighting.
Quantity of motion: A single summary measure of how much movement occurs in a recording, often computed by comparing successive video frames.
Reduced listening: Schaeffer’s practice of attending to the qualities of a sound itself while setting aside its cause and meaning.
Resonance: The tendency of an object or air volume to vibrate strongly at particular frequencies, amplifying and colouring a sound source.
Reverberation: The persistence of sound in a room after the source stops, produced by many overlapping reflections and quantified by the T60 decay time.
Rhythm: A pattern of durations formed by the intervals between perceived sound events, which may or may not be periodic.
Room modes: The resonance frequencies of a room at which standing waves form between its surfaces, causing uneven bass response.
Saccade: A rapid jump of the eyes between fixations, lasting tens of milliseconds, during which visual intake is largely suppressed.
Sampling rate: The number of amplitude measurements taken per second when digitising a signal, which must exceed twice the highest frequency to be captured.
Schizophonia: Schafer’s term for the split between a sound and its original source that recording technology makes possible.
Shepard tone: An illusion built from octave-spaced components that seems to rise or fall endlessly in pitch.
Sound-accompanying actions: Movements made to sound rather than for producing it, such as dancing or air-instrument playing, one category in the taxonomy of music-related body motion.
Sound-facilitating actions: Support movements that do not themselves produce sound but help performance, such as a pianist’s arm trajectories or breathing.
Soundmark: A sound with special significance for a community, the sonic counterpart of a landmark, such as particular church bells.
Sound object: Schaeffer’s term for the perceptual unit of listening, a chunk of sound of roughly half a second to five seconds heard as one event.
Sound-producing actions: Movements that generate sound directly, divided into excitation, such as striking or bowing, and modification, such as fingering.
Soundscape: The acoustic environment as perceived and experienced by people, including natural, human, and mechanical sources.
Soundwalking: The practice of walking through an environment while listening attentively, used both as an artistic practice and a research method.
Source–filter model: The standard account of the voice, in which the vibrating vocal folds provide a harmonically rich source and the vocal tract filters it through its resonances.
Source separation: Computationally splitting a mixed recording into individual parts such as vocals, drums, and bass, the machine counterpart of auditory scene analysis.
Spectral centroid: The centre of mass of a spectrum, a computational feature that correlates with the perceived brightness of a timbre.
Spectrogram: A representation of sound with time on the horizontal axis, frequency on the vertical axis, and energy shown as brightness or colour.
Spectrum: A snapshot of how the energy of a signal is distributed across frequencies, summarising the whole signal without showing change over time.
Standing wave: A stable pattern of reinforcement and cancellation formed when sound reflects between parallel surfaces, the cause of room modes.
Standstill paradigm: The experimental approach of asking participants to stand as still as possible while music plays, so that involuntary micromotion can be measured.
Stream segregation: The splitting of a sound sequence into separate perceptual streams, as when a fast alternation of high and low tones falls apart into two melodies.
Swing: A systematic long–short timing pattern at the subdivision level, with ratios in performance ranging from nearly even to well beyond triplet spacing.
Sympathetic nervous system: The activating branch of the autonomic nervous system, raising heart rate and skin conductance during intense musical moments.
Synaesthesia: A condition in which stimulation of one sense consistently triggers experiences in another, such as seeing colours for tones, distinct from the cross-modal correspondences most people share.
Synchresis: Chion’s term for the automatic perceptual welding of a sound and a visual event that occur at the same moment, the foundation of film sound design.
Syncopation: A local contradiction of metrical expectation, such as an accent on a weak beat or a silent strong beat, which creates rhythmic tension.
Tempo: The rate of the musical pulse, measured in beats per minute.
Timbre: The sound quality that distinguishes two tones of identical pitch and loudness, arising from spectral content and the temporal envelope.
Tonality: The organisation of pitches and chords around a central tonic, producing a learned hierarchy of stability among scale tones.
Tonotopy: The orderly arrangement of the auditory system by frequency, from the cochlea up to the auditory cortex.
Transduction: The conversion of energy from one form to another, as when a microphone turns pressure waves into voltage or a loudspeaker does the reverse.
Valence: The dimension of emotion running from unpleasant to pleasant, one axis of the valence–arousal model.
Valence–arousal model: A two-dimensional map of emotion, also called the circumplex model, that places affective states by pleasantness and activation instead of sorting them into discrete categories.
Ventriloquism effect: The capture of a sound’s perceived location by a plausible visual source, as when film dialogue seems to come from the actors rather than the loudspeakers.
Vibrato: A regular fluctuation of pitch, around five to seven cycles per second in singing, that adds warmth and helps a voice carry.
Window: The short segment of signal, tapered at its edges, that is analysed at each step when computing a spectrogram, with its size setting the trade-off between time and frequency resolution.