Hey @Dogba ,
is this referring to the internal microphone? If so, le'ts try the following test so we can see if there is an issue with the microphone.
1. From the phone dialler, enter *#0283#.
2. Select RCV Packet Loopback ON (it may appear as Start : RCV_1stMic on some devices).
Say a few words as if you were on a call. Can you hear your voice?
No problem at all! If you don't hear your voice it may mean that there is an issue with the microphone and the phone will need to be examined by one of our engineers.
Hopefully it fixes it. Can you respond in about a week and let me know if it fixed it? I dont want to go through the whole reset process if it doesn't work. Thanks!