This is what I call really cool project. Project itself is complex and requires some skills like Matlab and FPGA programming and even minor plumbing. First stage is a computer where Matlab GUI captures audio from any audio device like microphone. Then it calculates sound FFT and sends further data to FPGA board via LPT port.

ALTERA board then receives data from parallel port and according to FFT amplitudes controls 16 fountain pumps through Darlington resistor array. Project description contains plenty of videos and explanations on building this great device. Of course prototype is small enough - but if put in bigger scale it could be nice and modern attribute in various places. All project files are available here.