Detecting beat in an audio signal

Hi

Quick msp question. I want to detect beats (I think) from an incoming audio signal of a contact mic (a heartbeat). So far I've come accross beat~, bonk~ and fiddle~ (which I've used before) but not too sure which one I should be using or if there is another I've missed? Beat~ seemed to do nothing when I tested and bonk~ seemed to just capture everything.

Any help much appreciated.

Garrett