Comment 20 for bug 412862

I solved my internal mic problem for Lenovo Ideapad U330 by doing all of the following:
(Should work for Acer Aspire as well)

1. In terminal:
sudo apt-get remove linux-backports-modules-alsa-`uname -r`

2. Get latest AlsaUpgrade script here, along with directions on download, compile, install:
http://ubuntuforums.org/showthread.php?p=6589810

(It is AlsaUpgrade-1.0.23-2 as of 27Dec2010)

3. Download, compile, install AlsaUpgrade as discussed in #2.

4. After reboot, find out if you have installed the newer version of alsa. In terminal:
cat /proc/asound/version

5. If mic still does not work, type:
sudo gedit /etc/modprobe.d/alsa-base.conf

6. You should see something similar to:
options snd-hda-intel index=-2

7. Add this to the end:
options snd-hda-intel index=-2 model=XXXXX

where xxxxx depends on your machine.
Find out what you should put in xxxxx here: http://ubuntuforums.org/showthread.php?t=1043568
Acer Aspire user try adding "options snd-hda-intel index=-2 model=acer"

8. If your specific machine isn't listed, try using what is similar to your machine. For example, Lenovo Ideapad U330 isn't listed in http://ubuntuforums.org/showthread.php?t=1043568, but they do have other Lenovo machines listed and they are usually "model=lenovo".
I added "options snd-hda-intel index=-2 model=lenovo" to the end of my modprobe file.

9. Save, exit, reboot. Mic works for me now and in skype.