Thanks you two for your helpful input. I think dissecting a Singing Bass is an excellent place to start. And I've decided it's a good time to dive in and learn enough about basic electronics to understand what I'll need in terms of a power supply to operate whatever sensor system I come up with, but...

In search of advice! I'm working on an art installation and short of getting a degree in electrical engineering and starting from scratch, I'm stymied. Want to add motion-activated audio, remotely powered, without crazy amounts of cash required. Any thoughts?