Comment 17 for bug 412862

A little further investigation has shown the following:

The meter on the pulseaudio volume control input devices tab shows L/R cancellation regardless until there is a difference between the faders.

A pulseaudio volume meter showing levels for Internal Audio Analog Stereo shows mic audio on both channels but it's meter on the recording tab shows nothing until there is a difference between the faders on the input devices tab.

gnome sound recorder shows level on it's meter even when there appears to be cancellation and it has nothing showing on it's meter on the recording tab. Pulling down the left fader on the volume control input devices tab affects the level on it's meter whereas the right fader has no affect but this should not be taken as evidence of anything as it may be that the sound recorder is metering only left.

What do I suspect is happening - that the metering in Pulseaudio is showing difference between left and right rather than the sum and that skype is being clever and selecting that same 'bus' because it expects it to be mono rather than selecting the stereo bus and doing it's own downmix.

Just a guess.

--sean