Callers can't hear me. Only with loudspeaker on. Oneplus One

[seq1245]

Hi,

For a few days now callers cannot hear me in phone calls unless I enable loudspeaker. Testing with my wife we found that I am audible to caller but so very faintly it sounds very far away.

I believe the culprit has something to do with bluetooth. I have been using bluetooth headphones for around 4 months. I have taken phonecalls using the headphones about 4x over this period. I believe after the 4th call it resulted in this effect. I believe that somehow when I now take calls the phone is somehow tricking itself into thinking it has bluetooth headphones connected and is trying to pick up sound from the microphone on the headphones and the reason it works with loudspeaker enabled is this "force disables" the attempt to pick up sound from the headphone microphone somehow.

I have googled this issue many times and gone through many threads trying the different solutions offered. People have been posting since 2012 and earlier about similar issues with a range of different phones. In almost all cases enabling loudspeaker allows people to make calls but the caller cannot hear them without loudspeaker enabled.

https://productforums.google.com/forum/#!topic/Nexus/qJRGKkh4xX0
This thread, the author lists links to multiple other phone threads with same issue including the Oneplus One.

What I have tried:
1) "Ok Google" turn off. This is the most recommended solution. However my "OK google" detection on any screen was already off, so I tried enabling and setting it up and then disabling and had no success.
2) Turn bluetooth off. Or turn bluetooth on and off. Or turn bluetooth off then restart the phone. I tried this but none of these combinations helped.
3) Clean out the microphone. I did this with a small pin, nothing was dislodged. But seeing as calls work using loudspeaker I don't think it is the problem. Also if you shout quite loud into the mic at the bottom of phone the other user can hear you, but ofcourse you don't want to be screaming into a mic just to be heard.
4) Turn loudspeaker on and off a few times with a call active. No result.
5) Install app "SoundAbout". No result.

Phone details:
Oneplus One
Android 6.01
CyanogenMod 13.1.2
Not rooted

What can I try now to troubleshoot and ideally fix this problem?

Thanks

 

[B. Diddy]

Welcome to Android Central!

3) Clean out the microphone. I did this with a small pin, nothing was dislodged. But seeing as calls work using loudspeaker I don't think it is the problem. Also if you shout quite loud into the mic at the bottom of phone the other user can hear you, but ofcourse you don't want to be screaming into a mic just to be heard.

Speakerphone typically uses the secondary mic (at the top of the phone), which is why people can still hear you on speakerphone, even when the primary mic is having problems.

It's very possible that the primary mic itself is faulty. You may have to bring it to a repair shop to replace that part.