I bought a Pluto Trigger a week or two ago, and this was my first chance to try it out.
It's a nifty wee camera trigger, with a variety of sensors - passive IR, optical, and sound. I thought I would try the sound trigger by bursting a balloon that was part-filled with water, part blown up.
The trigger performed flawlessly, focusing was perhaps not quite so accurate.
I'll try again - in the better weather!