Show HN: Live breath detection and biofeedback from a phone microphone

Hi everyone, I am Felix, a famliy doctor from ZH, Switzerland.
A couple of month ago I started this little project called
shii • haa, a breathing app that uses the phone`s microphone
for live biofeedbackMy prior work in emergency medicine and intensive care was
closesly linked to breathing, mostly in critical situations...
and let me to reevaluate my own way of breathing. over time
one question popped into my mind: can medical knowledge and
biofeedback make an app actually promote self-awareness instead
of attaching your goals to the award system of the app.it combines signal processing, a breathing state machine and ML.
The state machine follows inhale, exhale and transitions in the
mic signal. A quality layer rejects noisy or ambiguous windows
before signals are used for feedback. All processing is done
on-device, no speech or raw audio is uploaded.What I'm trying to avoid is turning breathing into another score
or game. The app gives feedback on rhythm, depth and regularity,
but the point is more "notice what you are doing" than "perform
well".I'd be interested in feedback, especially from people who have
worked on signal processing, health UX, or Android/iOS audio
issues.