Polyphony is the maximum number of notes (or, more precisely, individual sound-generating "voices") a digital piano can produce simultaneously.
Why it's higher than it sounds like it should need to be
Playing a single note with the sustain pedal held, layering two sounds together, and the natural decay tail of previous notes all consume polyphony at the same time - so a piece that sounds like it only uses a handful of notes at once can use far more voices than expected, especially with sustain pedal use or layered sounds.
What to look for
- Entry-level instruments commonly offer noticeably lower polyphony than higher-tier ones; running out during heavy pedal use or layered sounds causes notes to cut off abruptly ("voice stealing" - see our synthesizer article on the same concept, which applies here too).
- For a beginner playing mostly single-line or simple pieces, lower polyphony is rarely a practical problem; for advanced classical repertoire with heavy pedaling, or for layering sounds, higher polyphony matters more.
Beyond the polyphony number, the underlying sound engine and sample quality (or physical modeling quality on higher-end instruments) affects perceived sound quality at least as much - a spec sheet number alone doesn't guarantee a piano sounds good.
