m8 when calling i cannot hear well

when calling i cannot hear the other person volume is very low but i set it to maximum somebody help me. i did not drop my phone or anything
when putting in speaker its working very well
i think there is something broken inside
is it possible to repair it?
i have 9.3.18
now i have upgraded to 9.6 but nothing seem to have change
reset factory registry reset also format the disk partition

update
i did check via
-windows explorer.exe the Volume settings
-volume bar in M8sprite.
-Use an earphone jack plugs in and out many times.

but it doesnt seem to repair the problem there is a problem with the hardware i guess is there anyway i can repair the speaker? how much would it cost

can somebody help me

Do u have M8Profil, look at the settings if your settings all correct or check under windows explorer.exe your Volume settings

I used to have the same problem. These might help
1.Check your volume bar in M8sprite.
2.Use an earphone jack plugs in and out many times.

i checked it but it still doesnt work