Comment 15 for bug 771633

Is this definitely a Raltek codec issue? There have been a few reports of no mic since upgrading to Natty... personally I'm also using hda-intel but with the IDT 92HD73C1X5 codec. Besides for the title, this bug report is still the most relevant bug report for me.

I eventually worked this out... gnome-volume-control (aka sound preferences) doesn't set things up correctly. Running alsamixer from a terminal is required (thanks to all those above who suggested this). My inputs will probably be different from the Realtek users, but these are the settings and my observations (from left to right, after pressing F4 for Capture settings):

Mic: 0 (makes no difference)
* Capture: 0 (volume makes no difference), MUST be set to capture (press space)
Capture 1: 0 (volume makes no difference), "capture" on this one makes no difference
* Input source: MUST be set to Internal Mic 1
Input source 1: makes no difference
Internal mic: makes no difference
* Internal mic 1: affects mic volume

"Capture" (not Capture 1) and Internal Mic (not Capture 1) affect the volume level shown in gnome-volume-control, but obviously have no impact on the actual mic volume.

Of course, this is all with my laptop's built in mic... I haven't tried plugging in an external mic. I've tried all the Input -> Connector Settings in gnome-volume-control but none of them set things up right (all 3 options give no sound). Besides volume problems (of the mic) when trying to use gnome-volume-control, the bigger issue is that when selecting 'Internal Microphone' from the list, it sets 'Input Source' to 'Internal Mic' instead of 'Internal Mic 1'.

Hope this helps other people too.