Very interesting idea, I hope you can progress this into a well working, proven application.
I tried to do something very similar a year or 2 ago, more directed towards meditation. (Ie as a helper that uses breath to detect a wandering mind). A microphone in itself wasn't sufficient in my case, and detection was quite hard. I ended up using wired earbuds with microphones.
Nice focus as well, less scoring and more signal. All the best in your project!
Thank you so much for your kind words. The microphone is the hard part, so I am trying to learn where the limits are instead of just pretending they do not exist... What happened to your project?