Comment 9 for bug 412862

Apologies for double posting but I found a few minutes to do some more testing. I have an Acer Aspire One 532h which has exactly the same symptoms i.e internal mic doesn't work until there is a level difference between right and left.

Not only is there a polarity reversal but working around this by reducing one input fader to zero is creating excessive noise because the phase cancellation is happening somewhere in digital and reducing the fader is not the same as muting the channel. I can further confirm this because an external signal (1KHz tone in this case) connected to only left or right with both faders the same, works fine and is clean compared to the fader down solution but the same source is suffering from cancellation when applied to both channels ( great for vocal removal :-) )

The scary thing is that installing pavucontrol and pulling the fader down has been offered all over the internet as a solution when in fact it's a poor workaround for one situation only.

Symptoms are the same with version 1.0.23 of alsa installed.

Sean