Automated Dialogue Replacement. Re-recording dialogue in a studio to replace unusable production sound. Also called "looping." The post-production process of restoring or improving recorded speech to match picture.

Building complex timbres by summing sine waves at controlled frequencies and amplitudes. Theoretically any sound can be reproduced as a sum of sinusoids. The Hammond organ is the analog example; FM synthesis is a computational shortcut.

The continuous background sound of a scene or environment — crowd noise, wind, mechanical hum, room tone. Distinct from Foley and dialogue, ambience provides the acoustic world that contains all other sounds.

Dolby's object-based spatial audio format. Places sounds as 3D objects in space rather than channels, enabling reproduction at any speaker count. The standard for theatrical and streaming immersive audio since 2012.

A shared signal routing path that combines multiple audio signals into a single output. In mixing, buses allow groups of sounds (all dialogue, all Foley) to be processed together. Essential in film mixing for stem management.

Applying the acoustic "fingerprint" (impulse response) of one space or object to another signal. A convolution reverb places any sound inside a real captured space. Also used for cabinet simulation and creative spectral processing.

A time-based effect that produces one or more echoes of a signal. In sound design, delay creates space, depth, and rhythmic interest. Short delays (1–30ms) create thickening and widening; longer delays create distinct echoes.

A time-varying control signal with four stages: Attack (rise to peak), Decay (fall to sustain), Sustain (held level), Release (fade to silence). ADSR shapes amplitude, filter, or any parameter over the lifetime of a note or event.

A processor that attenuates specific frequency ranges. Low-pass filters remove high frequencies; high-pass remove lows; band-pass isolate a frequency band. The foundational tool of subtractive synthesis and spectral shaping.

Frequency Modulation synthesis. One oscillator (the modulator) modulates the frequency of another (the carrier). At high modulation depths, complex non-harmonic spectra emerge — producing metallic, bell, and percussive timbres. Yamaha DX7 is canonical.

Recording and creating sound effects in synchrony with picture, named after Jack Foley. Includes footsteps, clothing movement, and prop handling. Performance-based, recorded to picture in a Foley stage. Distinct from field recording and synthesis.

The acoustic fingerprint of a space — recorded by playing a sine sweep or impulse and capturing the result. Used in convolution reverb to place sounds inside real spaces. Field recordists capture IRs to preserve locations acoustically.

The level of inherent electronic or environmental noise in a recording system. A lower noise floor allows quiet sounds to be captured without artifacts. Determined by microphone self-noise and preamp noise — critical specifications for field recording.

The primary sound source in most synthesizers. Produces continuous periodic waveforms — sine, sawtooth, square, triangle, noise — whose fundamental frequency determines pitch. Voltage-controlled oscillators (VCO) form the basis of analog synthesis.

The persistence of sound in a space after the source stops — the sum of all reflections. Reverb places sounds in acoustic environments and is fundamental to cinematic sound design. Convolution reverb uses real measured spaces.

Recording a real sound and playing it back at different pitches and timings. The bridge between field recording and synthesis. Modern sample libraries combine thousands of recordings to recreate acoustic instruments and environments with synthesis control.

The craft of creating, recording, and manipulating audio to serve a narrative, interactive, or aesthetic purpose. In film, sound design encompasses all non-musical sound — effects, ambience, Foley — and their integration with the image.

Separate mixed tracks for each major element of a film's audio — dialogue stem, music stem, effects stem. Stems allow re-mixing for different formats (theatrical vs. streaming), languages, and territories without rebuilding the entire mix.

Starting with a harmonically rich waveform (sawtooth, pulse) and using filters to subtract frequencies. The dominant synthesis paradigm — Moog, Prophet-5, 303. Filter cutoff sweeps are its signature gesture.

The electronic generation of sound from mathematical principles rather than physical acoustic sources. Encompasses subtractive, additive, FM, granular, physical modeling, and spectral methods. The core technology of sound design beyond recording.

The initial high-energy, non-periodic portion of a sound — the attack before steady-state sustain begins. Transients carry sonic identity: we recognize instruments primarily by transient shape. Transient preservation or removal is a primary sound design tool.

The visual representation of a sound as amplitude over time. The shape of a waveform determines its harmonic content — sine is pure, sawtooth is rich in harmonics, noise is aperiodic. Reading waveforms is the fundamental literacy of sound design.