Trigger sample with metro

This program triggers a sound repeatedly, and changes the sound's playback rate with each repetition. The sound file is so short that there's really no need to turn it off with a 0, so we just start it with a 1. The playback rate is calculated so as to cause a random transposition from -12 to +12 equal-tempered semitones, using the twelfth root of 2; the number of semitones (x) of transposition is determined by setting the rate to "2 to the x/12 power". You can put the patch into Presentation mode, which will present a cleaner user interface.