Default Phone call mic sounds quiet for other people

When I call people or they call me the microphone sounds quiet on the other end unless I talk loudly or put it closer to my mouth. On speaker they can hear me clearly and when I recorded a video it sounds clear. Does anyone know how to fix? I don't want to take my phone to AT&T to replace it...

I'm running Cyanogenmod 10.2 (don't want to update cause I like 4.3)
S-off (hboot 1.55)
TWRP 2.6.0.1