Polyphony means the number of notes or voices an instrument can sound at the same time. It can also describe music with multiple independent parts, but in synthesizer settings it usually refers to the maximum number of simultaneous voices.
One note may use several voices
Pressing one key does not always consume only one internal voice. Unison, layered sounds, and some stereo samples can use multiple voices for a single note. Holding previous notes with a sustain pedal increases the total further.
What happens at the limit
When the maximum is exceeded, the instrument automatically stops an older, quieter, or lower-priority voice. This is called voice stealing. If chord tails disappear unexpectedly, the polyphony setting may be too low.
Choosing the right mode
Pianos and pads often need a higher voice count. Bass and lead sounds may work better in monophonic mode, where only one note plays at a time and legato or portamento behavior is easier to control. Match the setting to the part.
CPU and memory use
A higher limit allows more voices to run and can increase CPU and memory use. Instead of setting an unlimited value, find the lowest setting that preserves the required notes and release tails in the actual performance.
Related terms
See Unison for stacking voices on the same note and Mono / Monophonic for single-note behavior.
