The synth glossary
Synth terms in plain English, cross-linked to playable demos.
Synthesizers come with their own dialect — cutoff, resonance, ADSR, FM. Here is the whole vocabulary in plain English, colour-coded by kind and cross-linked to the Academy topic and the instrument where each idea shows up. 85 terms in all.
A
Additive synthesis
synthesisBuilding a sound up from nothing by stacking pure sine waves at different frequencies and levels.
ADSR
shapingThe four-stage shape of a classic envelope: Attack, Decay, Sustain and Release. It shapes how a note swells in, settles and fades.
Amplitude
soundThe height of a wave — how loud it is. Bigger swings mean a louder sound.
Approach note
soundA note one step above or below a target, played just before it to create a small pull into the destination.
seeBasslines
Arpeggiator
rhythmA device that takes a chord and plays its notes one at a time, in a repeating pattern.
seeCascade
Arrangement
gearThe large-scale order of a track — what plays in the intro, main section, break and ending, and when each part arrives or leaves.
seeArrangement
Attack
shapingHow long a note takes to reach full volume after a key is pressed. Fast is a pluck; slow is a swell.
B
Backbeat
rhythmThe strong snare or clap on beats two and four in common four-beat music — a simple anchor for many grooves.
Bandpass filter
shapingA filter that passes a band of frequencies in the middle and cuts everything above and below it.
BPM
rhythmBeats per minute — the tempo, or speed, of the music.
C
Carrier
synthesisIn FM synthesis, the oscillator you actually hear — the one whose pitch the modulator bends.
seeFM
Chorus
effectAn effect that thickens a sound by mixing in slightly detuned, delayed copies of it.
Cutoff
shapingThe frequency where a filter starts working — for a lowpass, everything above it is turned down.
seeSubtractive
D
DAW
gearDigital Audio Workstation — software for recording, arranging and mixing music. PlasticSynth's Studio is a tiny one.
Decay
shapingIn an envelope, the drop from the attack peak down to the sustain level.
Delay
effectAn echo effect that repeats the sound after a set time. Feed it back on itself and the echoes repeat.
Detune
soundShifting an oscillator slightly off pitch. Layering detuned copies gives a thick, shimmering sound.
E
Envelope
shapingAn automatic control that changes a value — usually volume — over the life of a note. See ADSR.
Euclidean rhythm
rhythmA pattern that spreads a number of beats as evenly as possible across a number of steps — the basis of many world rhythms.
F
Filter
shapingA tool that removes or emphasises part of a sound's frequency range — the heart of subtractive synthesis.
seeSubtractive
FM synthesis
synthesisFrequency modulation — using one wave to wobble another's pitch thousands of times a second, creating new harmonics.
Frequency
soundHow fast a wave vibrates, measured in hertz. Frequency is what sets the pitch.
Fundamental
soundThe lowest and usually strongest frequency in a tone — the pitch you actually hear.
seeWaveforms
G
Gain
soundAnother word for volume or level — how much a signal is turned up or down.
Generative
rhythmMusic made by a system of rules that plays itself, rather than a fixed pattern you program.
Glide
shapingA smooth slide in pitch from one note to the next, instead of jumping. Also called portamento.
seeAcid
H
Harmonic
soundA frequency at a whole-number multiple of the fundamental. The mix of harmonics gives a tone its character.
Headroom
soundThe safety space between ordinary signal peaks and the maximum level, left so several parts can add together without clipping.
Hertz (Hz)
soundCycles per second — the unit of frequency. 440 Hz is the A that orchestras tune to.
Highpass filter
shapingA filter that passes high frequencies and turns down the lows — useful for thinning a sound out.
I
Index
synthesisIn FM, how hard the modulator pushes the carrier — effectively the brightness of the tone.
seeFM
Inharmonic
soundPartials that are not neat multiples of the fundamental, giving metallic, bell-like or clangy tones.
seeModal
Inversion
soundA chord with the same notes reordered so a note other than the root is at the bottom; useful for smooth voice leading.
K
Karplus–Strong
synthesisA physical-modeling technique that makes a plucked string from a burst of noise circulating a tuned delay.
Key
soundThe root note and scale a piece is in. A shared key keeps every instrument sounding in tune together.
L
Leslie
effectA rotating speaker cabinet that gives organs their swirling, chorused motion. Spins slow or fast.
seeOrgan
LFO
shapingLow-Frequency Oscillator — a slow wave used to wobble something else, like pitch (vibrato) or volume (tremolo).
Lowpass filter
shapingThe most common filter: it passes low frequencies and turns down the highs, making a sound darker.
seeSubtractive
M
MIDI
gearA standard that lets instruments and software send notes and control messages to one another.
Modal synthesis
synthesisModelling the few ringing frequencies (modes) of a struck object like a bar or bell.
Modulation
shapingUsing one signal to change another — an LFO on pitch, an envelope on the filter, and so on.
Modulator
synthesisIn FM, the oscillator you don't hear directly — it bends the carrier's frequency to add harmonics.
seeFM
Monophonic
gearAble to play only one note at a time. Basslines and leads are often monophonic.
Motif
soundA short, recognisable musical idea — usually a small rhythm and contour — that can be repeated and varied.
N
Noise
soundA random signal with no clear pitch. It's the raw material for percussion, wind and the pluck in a string.
O
Octave
soundA doubling (or halving) of frequency — the same note, an octave higher or lower.
Oscillator
synthesisThe part of a synth that generates the raw, repeating tone before anything shapes it.
Overtone
soundAnother word for a harmonic above the fundamental.
P
Panning
effectPlacing a sound between the left and right speakers to create width and separation.
Partial
soundAny single frequency component in a sound, whether it lines up as a harmonic or not.
seeModal
PeriodicWave
gearThe Web Audio object that stores a custom single-cycle waveform, built from its harmonic recipe.
Physical modeling
synthesisSynthesis that simulates the physics of a real instrument rather than recording or filtering.
Pitch
soundHow high or low a note sounds. It's set by the frequency of the wave.
Polyphonic
gearAble to play several notes at once — needed for chords and pads.
Q
Quantize
rhythmSnapping notes onto the nearest beat, or the nearest note of the key, so nothing is out of time or out of tune.
R
Ratio
synthesisIn FM, the modulator's pitch compared to the carrier. Whole numbers ring like bells; fractions turn metallic.
seeFM
Resonance
shapingA boost in the frequencies right around a filter's cutoff, adding a whistle or squelch. High resonance is the acid sound.
Root
soundThe note a chord or key is named after — its strongest sense of home and the safest first bass note.
S
Sawtooth
soundA bright, buzzy wave containing every harmonic — the richest raw material for subtractive synthesis.
seeWaveforms
Scene
gearA saved musical section in the Studio that remembers each track's pattern and mute state, such as Intro, Main, Break or Drop.
seeArrangement
Sequencer
rhythmA device that plays a pattern of notes in time, over and over, so you don't have to.
Sine
soundThe purest wave — a single frequency with no harmonics at all. Soft and hollow, like a whistle.
seeWaveforms
Square
soundA hollow, woody wave that contains only the odd harmonics. The classic chiptune tone.
seeWaveforms
Subtractive synthesis
synthesisStarting with a harmonically rich tone and carving harmonics away with a filter — the classic analog method.
Sustain
shapingThe volume a note holds at while the key stays down. It's a level, not a length of time.
Swing
rhythmDelaying the second subdivision in each pair so even timing becomes a long–short feel without changing tempo.
Syncopation
rhythmEmphasising an offbeat or normally weak part of the bar, creating surprise and forward pull.
T
Tempo
rhythmThe speed of the music, measured in beats per minute (BPM).
Timbre
soundThe character or colour of a sound — what makes a trumpet and a flute at the same pitch sound different.
Transient
soundThe short, loud burst at the very start of a sound, like the click of a pluck or the thud of a drum.
Tremolo
effectA wobble in volume driven by an LFO — the shimmer of a vibraphone or a Leslie.
Triangle
soundA mellow wave with only a few quiet harmonics — softer than a square, reedier than a sine.
seeWaveforms
U
V
Velocity
gearHow hard a key is struck, usually mapped to the volume or brightness of the note.
Vibrato
effectA gentle wobble in pitch, driven by an LFO.
Voice
gearOne note's worth of sound. A synth's polyphony is how many voices it can play at once.
Voice leading
soundConnecting chords so each individual note moves as little and as smoothly as possible.
W
Waveform
soundThe shape of one cycle of a sound wave. Its shape decides the harmonics, and so the timbre.
seeWaveforms
Wavetable
synthesisA set of single-cycle waveforms you scan through for shifting, evolving timbres.
Wet / dry
effectThe balance between the processed (wet) signal and the original (dry) one in an effect.