Default [Q] Noise cancellation mic problem?

I am having a weird issue. People have been complaining that they cannot hear my voice clearly on the call, or its very low. I need to be very loud for them to hear me alright. I tried all different radios and it was the same.
I figured out that if I cover the noise cancellation mic on top with my finger and talk, they can hear me perfectly fine even if i am not loud. Is this a know problem and is there anyone facing similar issues? I will appreciate any help

Thanks.

Edit: I have also tried different roms, both stock and kitkat.