I have an HTC One with a faulty primary mic, I have concluded it to be a hardware problem because its condition is the same after installing various different custom ROMs (the mic became faulty while on the stock ROM). I am using Viper ROM at the moment.
Now, with this problem, I have to use the mic from my earphones everytime I make a call. I am mostly OK with that, but I am trying to find ways where I should be able to use it without external mic in case I forget to carry my earphones/mic with me.
I was running the HTC Function Test the other day and discovered that my device comes with a secondary mic at the back of the phone, which works absolutely fine when I tested it. The recording (while holding as if I was talking on the phone) and playback from that mic was perfect. It would be really useful if I could either make it my primary microphone (calls, recordings, etc.) or atleast use it for phone calls. I don't know if there is a way from the hardware perspective, but I am quite sure we could do it by changing properties from within the build.
This is my first ever question, and I am counting on this community for the solution.