Noise using internal mic

I have Inspiron N 4050 and during voice chat on Skype, other party listens nose on their speaker and can't listen me. If I use external mic after plugging in, everything works fine. In audio setup from control panel, If i select "Listen to this device" for internal mic, I also listen nose from my own speakers. There is an audio driver IDT 92HD87B1 available at dell.com for my model laptop which is for nose issue with skype. I have installed this driver but problem remains the same. Any feedback to resolve this issue will be appreciated.

Thanks

Salman