Since I've blogged about my recent skype issues. I've played a lot with pulseaudio, alsa, alsa-oss to experimented a lot until I figured out why Skype was failing to properly delivery sound and record via my embedded laptop mic.
Anyways, while researching on the cause of my Thinkpad r61 mic issues, I've red a bunch of blog posts by people experiencing microphone oddities with Lenovo Thinkpads
Throughout the search I come across one very good article, which explained that in many cases the Thinkpad sound problems are caused by the snd-hda-intel alsa kernel module. snd-hda-intel fails to automatically set proper sb model type argument during Linux install when the soundcard is initialized with some argument like options snd-hda-intel model=auto
Hence, the suggested fix which should resolve this on many Thinkpad notebooks is up to passing the right module argument:
To fix its neceessery to edit /etc/modprobe.d/alsa-base.conf .
debian:~# vim /etc/modprobe.d/alsa-base.conf
Find the line in the file starting with:
options snd-hda-intel model=
and substitute with:
options snd-hda-intel model=thinkpad
Finally a restart of Advaned Linux Sound Architecture (alsa) is required:
debian:~# /etc/init.d/alsa restart
At most cases just restarting the alsa via its init script is not enough, since the ssnd-hda-intel kernel module is already in use by some program or something, so its best to do a reboot to make sure the module is loaded with the new model=thinkpad argument.
My exact laptop sound card model is:
debian:~# lspci |grep -i audio
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 03)
After changing the module and using alsamixer and aumix to make sure mic is unmuted and its volume is high enough, mic sound rec works fine.