Little Atlas Heavyweight wrote:this would be a funny way to find your heart keeps lousy time. i.e.-a murmur.

'Lousy time' would be a dysrhythmia - tachycardia is an abnormally fast heart rate, bradycardia an abnormally slow one.
A cardiac murmur is an audible manifestation of turbulent blood flow in the heart, usually caused by a narrowed or leaky heart valve.
I listen to my heart a lot!

Thanks for the advice, I'm going to start making some prototypes soon (and for those who've already, would you post some pictures?).

I read about someone who built one, and after wearing it constantly was able to (reportedly) control their heartbeat with their mind. By focussing, they could increase and decrease it's pace, which seems a) somewhat suspect, and b) dangerous.

I'll get on that midi in thing too.

Have you tried a drinking glass - like when you listen on the room next to you by pressing a drinking glass on the wall? I'm just thinking you could use your body as a membrane. There's got to be some old-school, pre-stethoscope invention that you could hit with a shotgun...