Polyphony is how many notes a synth can play at the same time. A monophonic synth plays one note; a polyphonic synth plays a whole chord. That one number decides whether a synth is built for basslines and leads or for chords and pads, and it is one of the first things worth checking about any instrument.
This applies to any synth or plugin, in any DAW or a browser instrument. Voices, glide and voice stealing mean the same thing wherever you meet them. None of it is tied to one product.
Polyphony is how many notes a synth can play at the same time. A synth with high polyphony can hold a full chord and let it ring; one with no polyphony can sound only a single note, so each new note cuts off the last. The word simply counts simultaneous notes, nothing more, and it is one of the first things worth knowing about an instrument before you play it.
Polyphony is a property of the whole synth, not of any single knob. It sits alongside the oscillator, filter and envelope covered in our guide on what a synthesizer is, and it decides whether those parts serve one note or several at once. It says nothing about which notes you play, only how many can sound together.
Count the notes you can hold down and still hear. One note at a time is monophonic. Several notes at once is polyphonic, and the number a synth can manage is measured in voices. Everything else on this page is detail hung on that one idea.
A monophonic synth plays one note at a time, while a polyphonic synth plays several at once. Press a second key on a monophonic synth and it drops the first and sounds the new one; press a chord on a polyphonic synth and every note rings together. That single difference decides what each is good for.
Monophonic synths are the classic choice for basslines and single-line leads, the parts where only one note sounds at a time anyway. Because a monophonic synth is always moving from one note to the next, it often offers glide, also called portamento, which slides the pitch smoothly from the old note to the new one instead of jumping. That slide is a signature sound in a lot of synth bass and lead playing, and it is one reason a monophonic synth still earns its place. If you are writing low parts, our guide on how to make a bassline leans on exactly this kind of single-note playing.
Polyphonic synths are what you need for chords, pads and anything where more than one note has to sound together. The number of notes a polyphonic synth can hold at once is counted in voices, so an eight-voice synth can sound up to eight notes together. Play a four-note chord and you have used four of them; hold that chord and add more with the sustain pedal down and you climb toward the limit.
| Type | Notes at once | Best for |
|---|---|---|
| Monophonic | One at a time | Basslines and single-line leads, often with glide between notes |
| Polyphonic | Several, counted in voices | Chords, pads and anything with more than one note held together |
| Paraphonic | Several, but sharing one filter and envelope | Simple chords on a synth that is not fully polyphonic |
A voice is one note a polyphonic synth can play at the same time, so the voice count is its ceiling on simultaneous notes. An eight-voice synth can hold eight notes at once; ask for a ninth and something has to give. What gives is decided by voice stealing.
Voice stealing is what happens when you play more notes than there are voices. To free a voice for the new note, the synth cuts off one that is already sounding, usually the oldest, so the note you played first drops away to make room. Most of the time you never notice, because the oldest note is often the quietest or already fading. But on long, sustained chords, or with a heavy sustain pedal and a lot of held notes, you can hear earlier notes vanish, and that is the voice count showing through.
Modern software synths usually offer plenty of voices, sometimes thirty-two or more, so voice stealing is rarely a problem in a DAW. Hardware and older instruments tend to be tighter, and the limit is easier to reach. It matters most with slow pads and washes, where notes are held long enough to pile up.
Each active voice is another note the synth has to generate and shape, so more voices cost more CPU. On a busy project the tradeoff is real: a lush patch with many voices, running on several tracks at once, adds up. Higher voice counts give you safety from stealing, but they are not free, which is why synths let you set the number rather than leaving it wide open.
Paraphonic is a middle ground between monophonic and polyphonic. A paraphonic synth can sound several notes at once, but those notes share a single filter and a single envelope, rather than each having their own the way a fully polyphonic synth does. So it can play a chord, but it cannot shape each note of that chord on its own.
In practice this means the notes rise and fall together. Because one envelope governs the whole group, a fresh note added to a held chord does not start its own attack; it joins the shape already in progress. The result is chords that work, but with a slightly blurred, shared quality rather than the fully separate notes of a true polyphonic synth. Whether that is a limit or a character is up to you, and plenty of well-loved synths are paraphonic on purpose.
It helps to see the three as a scale of how independent the notes are. Monophonic gives you one note with its own filter and envelope. Paraphonic gives you several notes sharing one filter and envelope. Polyphonic gives every note its own, which is why it is the most flexible and also the most demanding to build and to run.
Polyphony makes far more sense when you can hear several notes ring together and then hear one drop away. Reading the theory gets you the map; hearing a chord hold is what makes it stick.
ARGISH is a self-playing synthesizer. It plays chords rather than single notes, so it is an easy place to hear polyphony in action: set a mood and a key, build a progression on the chord wheel, and it holds several notes at once and evolves them in the background while you listen. Because it plays itself, you can hear how a chord sits together rather than only read about it. It runs in your browser, or as a plugin in your DAW: an Audio Unit, a VST3, an AAX for Pro Tools and a standalone app.
You can hear it free in your browser first, no install and no account, then decide.
Everything on this page also works by hand on any synth, which is rather the point of writing it down.
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