Internal Mic stopped recording voice, but hears case/keyboard touching

Since this morning I am unable to record my voice on my Macbook Air 2012 internal microphone but the microphone can hear me touching the keyboard, the Macbook case…

I tried to tweak system preferences, enabling/disabling noise ambient reduction and so on without success. Tried to reboot a couple of times with no luck.

Any idea on what should I try next?

I’m on Mountain Lion (10.8.3).

Screen is

Go to system preferences, open Dictation & Speech. Under dictation, change default microphone to Internal Microphone if it is Automatic. If not, switch it to Automatic for a second and switch back to Internal Microphone. I know this sounds ridiculous, but it works.

my microphone is working on the side from your laptop use a needle to pinch and clean out the hole from the microphone

At the moment, my best guess is that the microphone has become dislodged from its spot in the side of the case and is now just sort of floating around inside. This would explain why it picks up all the taps and noises on the case but doesn't pick up anything else well.

Use a toothbrush and an up-and-down motion to clean the port. The microphone port on a Macbook air has incredibly narrow holes. A thin needle will only clear surface debris if that is what's causing the blockage..

Here's an instructional video: https://www.youtube.com/watch?v=6aWpC8N8W08