A control device used as an alternative to a keyboard, mainly for playing drum and percussion sounds. A drum pad is intended to be struck or tapped, with either drum sticks or the fingers. It generates a trigger signal which usually triggers an envelope generator to play a sound with a fixed envelope profile. It may also sense velocity. Most modern drum pads use a MIDI interface, and they do the triggering function by sending a note on message with the velocity if sensed, immediately followed by a note off.