Default [Q] Problem with microphone XT910S

Dear all
I have a problem with my XT910S, my micro phone is very small when i make a call, the other side can not hear my voice well, is that a problem with hardware or roms. My system version is 982.124.14.XT910.retail.en.AU , Baseband U_04.11.01P, Kernel version 3.0.8-g7198280 , build number 9.8.20-124_SPUEM-14 IMPROVE LITE, Android 4.1.2. Thanks for any help