MBP 15" audio input very bad quality The audio input of my MBP 15" 2011 is pretty bad no matter if the ambient noise reduction is checked or not. 

I've tried all kinds of sound adjustments from the control panel but I can't get it good.

In order to tell you what's the sound quality with words: If I make an audio call the other person doesn't hear me well and have to set an upper level to understand me. If I type something on the keyboard, then the callee become deaf instantly.

So the fan &amp; keyboard sounds are very loud whereas my voice is quite low. How can I (try to) fix this?
My checklist would consist of ensuring that the mic is not covered by dust/particles, try to use audio-recording software to make sure it isn't a problem with your voice chat software, and use an external mic to make sure it isn't a problem with the system itself.  One issue with the 15" MBP 2011 is that the mic is actually near the left speaker grille, so if you're running more intensive software that will run your fan up, you may have issues with fan noise being audible on the voice chat.  Typing will also result in noise on the mic, moreso on the left side of the keyboard.  It's a specific design issue with the 2011 MBP 15", and is noted by users on numerous Apple forums.  Making sure that the mic/speaker grilles are clean can help with the audio clarity; however, typing will always be audible on the mic.