Comment 253 for bug 116326

Good news for laptops with a Realtek ALC268 codec and an internal digital mic (like Acer TravelMate 6292) : Now it works in Karmic (thanks to Alsa 1.0.20).
But you need to modify You need to replace the following line in /etc/modprobe.d/alsa-base:
options snd-hda-intel power_save=10
with:
options snd-hda-intel power_save=10 model=acer-dmic
And then reboot (or reload the snd-hda-module).
After that, internal mics works.
Record level is a bit low but is works :-)