Have you ever looked at a spec sheet and thought to yourself, “What is polyphony?” Well, you’re not alone – this is something that most customers don’t actually really know much about, but for some people, it’s one of the most important specs on that keyboard information sheet.
Not to be confused with the use of the term in the context of music theory, especially when it comes to the polyphonic music of Bach, in this article, we’ll explain what it means and why it is important, in the context of digital pianos.
What is Polyphony on a Digital Piano?
The definition of polyphony is literally just multi-tonal, and in the case of digital pianos, it refers to the number of tones that the piano can sound at once.
If you google polyphony you might see other terms come up, such as homophony, monophony, or monophonic, but none of these terms are relevant when discussing polyphony in the context of a digital piano spec sheet.
If two keys are played at once, that’s a polyphony of “2”. If 5 notes are played, that’s a polyphony of 5. So the maximum polyphony is the maximum number of notes that can be played at once.
Since we only have 10 fingers to play the piano with, the need for greater polyphony is driven by the use of a sustain pedal, sounds that have longer release times, or layered sounds.
A good example would be a piano+strings layer – a very common pairing on digital pianos and often beautiful musical texture. Strings have an extremelyy long release time compared with pianos (when you let go of the note, the sound starts decaying, and takes 1-2 seconds to completely be silenced).
So if you were to play a large stacked chord using the sustain pedal, and also play some sustained scalar runs on top of that at the same time, a max 64-note polyphony could easily be hit.
Add a third layer, or have the scalar patterns played throughout the whole range of the instrument with the sustain pedal down, and you might even start to test the 128 polyphony limit.
What Happens When You Run Out of Polyphony?
When that maximum limit is crossed, the instrument will usually mute the oldest note which isn’t still actively being played on a key. It just goes silent.
For casual playing, this is unlikely to cause problems if the instrument has 64 polyphony (or around that range). However, if you are doing any recording, using rhythms, playing back a 16-track MIDI file (Format 1) or even just using layers in some kind of performance, there are going to be noticeable gaps in the playing, or even critical tones may be missing altogether.
For example, I have been in situations where a crash cymbal or bass drum kick on a major bar line was simply not played because I’d maxed out the polyphony, causing me to have to redo the sequence to free up some bandwidth on the tone engine.
Conclusion and Recommendations
How many notes of polyphony are right for you? The answer to this depends on your intended use and the playing situations you find yourself in most often.
If most of what you’ll be doing is ‘piano only’, then 128 max polyphony is going to be enough for all of the melodic lines you’ll be playing through the course of your music-making. If you could see yourself getting into layering with rhythms on a regular basis, getting something closer to the 192 or 256 max polyphony would be preferable if the model selection and your budget allow for it.
