I recorded the sound of a pen striking a half-full soda can. I loaded this into Sampler and went to the MIDI panel and mapped "Aftertouch" (pad pressure) to "Loop Length" with a value of -100. Now pad pressure modulate the loop length.
Here is a video of this sound design work in progress – http://youtu.be/Ld5KWyGs9_M.
Composer, Synthesist, Electronic Musician & Multimedia Artist | Sr. Systems Analyst | Founder of the Rocky Mountain Synthesizer Meetup