| Most commonly referred to as aftertouch.
1) The ability of a MIDI keyboard controller to change the amount of a MIDI parameter in a sound by pressing a key down after it has initially been pressed. Sometimes this function can also be used by non-keyboard controllers, such as wind controllers.This type of touch sensitivity is commonly used to bring in vibrato on wind instrument sounds.
2) The ability of a MIDI synthesizer or tone generator to respond to MIDI aftertouch messages. |