The voice inlet hole to the microphone may be blocked with lint etc. Try using a vacuum cleaner and see if this clears the obstruction.
DO NOT use a pin or probe to try and clear it as you may damage the microphone which is directly behind it.
+
+
=== Update (05/23/2018) ===
+
+
Hi @chedley ,
+
No I don't sorry.
+
This is the best that I can find.
+
Here is a [https://www.youtube.com/watch?v=KNgSDmkn96c|video] that shows the teardown of a LG V20.
+
Here is an image taken from the showing showing the mic (I think).
+
[image|1463589] (click on image to enlarge for better viewing).
+
I can't see any "flex cable" in the video/image for the mic so am wondering if the link I posted earlier was for the correct one. (I did say "if this is the one" hoping that you could tell when you opened the phone). You may have a better view when you've dis-assembled the phone to that point.
Hi @chedley ,
The voice inlet hole to the microphone may be blocked with lint etc. Try using a vacuum cleaner and see if this clears the obstruction.
DO NOT use a pin or probe to try and clear it as you may damage the microphone which is directly behind it.