Here you go, this is how it's done.
OK here is how I have my setup for those interested.
N D300, S105, Mumford timing device with a vibration sensor attached, 4"speaker covered with a 12" latex balloon. Macbook Pro, Milk, food coloring, 4 flash heads 1 connected to the timing device three remote. All flashes are mounted high front rear and two sides. drops of milk are put into the middle of the speaker, a sound is generated from the default sounds in the sound control panel. Timing device allows for a 1 millisecond advance, these shots are in the region of 20Ms to 30Ms. This is all done in a dark room with the camera on Bulb setting. Sequence is as follows... Open shutter, play sound (Pop, Ping, Bottle or other Etc). Speaker cone vibrates and is detected by the vibration sensor, timing device counts the allotted time the flashes fire, close shutter. Adjust timing to get the desired result. After every shot the speaker cover must be wiped dry as the drop of liquid will flow out if wet or damp. So it is very time consuming but very satisfying when you get a good result. With care you can blend colors before the shot to give some nice results.