Audio Effects & Signal Processing Terms

Audio Effects & Signal Processing Terms explains the tools and processes used to shape sound in music, film, podcasting, and other audio projects. It’s for producers, engineers, musicians, and anyone working with recorded or live sound.

The glossary covers terms like reverb, EQ, compression, filters, delay, and distortion. Each entry breaks down what the effect does, how it’s used, and why it matters. If you’re mixing tracks, designing sounds, or cleaning up a recording, this page helps you understand how audio tools change tone, space, and dynamics – without confusing jargon or vague explanations.

Distortion & Harmonics

Distortion – Adds harmonics by clipping, wavefolding, or bit-crushing the source.

Harmonic Distortion – Adds musically related overtones when gear saturates – sweet on guitars, harsh in converters.

Harmonics – Whole-number multiples of a fundamental that shape timbre and perceived brightness.

Dynamics & Level Control

Auto-Duck – Side-chain gain riding that lowers music whenever narration crosses a set threshold.

Clipping (Audio) – Hard cuts the waveform tops when signal exceeds 0 dBFS, introducing harsh distortion.

Compression – Reduces dynamic range by attenuating signals above a set threshold.

Dynamic Range – The span between the quietest and loudest parts of a signal.

Fade-In – Often uses exponential curves for a natural ramp-up in dynamic material.

Fade-Out – DJs time this curve to hit an exact post when talking over music.

Gain – Input level control that sets signal-to-noise ratio before any processing.

Headroom – The dB margin between the operating level and 0 dBFS, preventing digital clipping.

Input Gain – Sets level before ADC – too high clips, too low increases hiss.

Filters & EQ

All-Pass Filter – Alters phase across the spectrum while leaving amplitude flat, useful for phasers and delay compensation.

Audio Filter – A circuit or algorithm that boosts or cuts selected frequency bands to shape timbre.

Band-pass Filter – Lets only a mid-range slice through, perfect for “radio voice” FX.

Equalization (EQ) – Boosts or cuts frequency bands to fix tone or create space.

Equalizer – Hardware or plug-in with fixed or sweepable bands for fast tone shaping.

Filtering – Blanket term for shaping spectra with HPF, LPF, and parametric EQ moves.

Formant – Resonant vocal peaks that define vowel identity – pitch-shifters preserve them for realism.

Frequency – Cycles per second that our ears hear as pitch or timbre.

Hertz – Cycles-per-second unit used to mark EQ center frequencies and LFO rates.

High-Pass Filter – Rolls off sub-bass to stop plosives and stage-rumble.

Low-Pass Filter – Removes harsh highs – DJs sweep it for tension before a drop.

Notch Filter – Cuts a razor-thin band to remove hum or feedback without altering overall tone.

Noise Reduction & Restoration

Adaptive Noise Removal – A dynamic filter that tracks changing background hiss or hum and attenuates it frame-by-frame.

Background Noise – Typically reduced with spectral subtraction or multiband expansion.

Hiss – Broadband noise from pre-amps or tape, reduced with gentle high-frequency expansion.

Plug-in Platforms & Umbrella Terms

AU Plug-ins – Signal processors wrapped in Apple’s Core Audio framework, supporting parameter automation and latency reporting.

Audio Effects – Any processor that changes level, tone, space, or time to reshape the raw recording.

Time & Spatial Effects

Echo – Repeats the signal at timed intervals, creating a sense of space or rhythm.

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