This was a project I worked on with a Bio-engineering student during my last semester at Berkeley. It's based off a technique to detect bone fractures using a tuning fork and stethoscope (read about that here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2681212/). We had a working prototype done before I left the project, but I believe she's still working on it with a team at UCSF.
The code and enclosure files live here: https://github.com/IDD-su18/fractal.
Here's a video presentation I made about it: