A trigger pad is an electronic sensor on a drum that produces a certain sound assigned from a sound module once the head has been struck. This device allows drummers to play at a constant dynamic regardless of the physical force used.
Triggers are also used to add more definition to drum sounds and prevent bleeding[when defined as?] between sound sources, making it easier to hear clearly every drum hit without rumble or excessive cymbals. An example[according to whom?] is where very rapid bass drum hits become difficult to distinguish or even hear in the presence of a full band.
Triggers are used to count and monitor drum hits, usually[according to whom?] as a training device (e.g., to see if a drummer misses hits), and to officially monitor tests and competitions of drumming speed.
Mike Portnoy uses an electronic drum pad with a hardwired electronic metronome as what he calls the "secret cowbell", to count off the songs in a way that only his fellow band members and the technicians can hear.