Polypressure [polyphonic key pressure, polyphonic aftertouch]
- Brandon Smith
- , revised by Anne Beetem Acker
[polyphonic key pressure, polyphonic aftertouch]
On an electronic instrument, an expressive MIDI characteristic or data type (in the form: channel, note number, pressure) that transmits the key pressure for individual keys, and therefore separately for each note played, even when several are played simultaneously. This allows the performer to play different notes simultaneously at different loudness levels or with other effects, such as adding vibrato or triggering a filter. As with the more common monophonic MIDI data type (which averages the pressure for different keys pressed simultaneously, as if all were played with the same pressure), the pressure value is transmitted when the performer strikes a key while it is depressed, allowing the tone to change while a note is held.
The term ‘polyphonic aftertouch’ is also used to describe controllers (usually keyboards) with the capability to sense and send polypressure MIDI data, a characteristic found only in relatively expensive equipment. In velocity-sensitive keyboards without aftertouch, only the speed with which the key is initially depressed is sent as data....