Does android allow that an app could process incoming call audio?
This is a disability related requirement, for a user who is distressed by extraneous sounds from poor quality microphones and muzac systems. It's mostly a case of filtering out high frequencies that are largely irrelevant for understanding speech, but it would be particularly nice if I could analyze whether there is a voice speaking, or on-hold muzac, and mute or replace the muzac.
Where would I start looking at how this works? What libraries and interfaces should I be reading about? Are there any simple open source apps I could look at for example code?
I've got a bit of DSP and AI background, and general coding experience, but not an Android programming background. It is probably only viable for me to write this app if I can find a starter project which gets me close to what I want. Of course if there is an existing app that could help I'd love to hear about it.