Default Problem with mike!

I have a Qtek9100 with soft 6.5.0.0. I am new to this mobile and do not understand everything better. However more or less goes well.
But i have a problem with mike.I speakers hear very well
and he me hearing very bad with more noise.
I asked many people, but no one gave an answer with professional, saying that these phones have this problem from the plant itself.
Is this true or problem is solvable?????
If so how can I solve this problem?