Comment 19 for bug 639846

To clarify previous posts. In alsamixer, when viewing capture controls, there are 4 sliders.
3 of them (Mic boost, capture 1, digital) appear to have no effect on the internal mic.

For me internal mic works best when Left channel of Capture control is set to zero, and right channel is set high.
(Use PgDown to zero both channels, then E key to raise only right channel, C key to lower it)