For release Squeeze or any later release, alsaconf is no longer available in package
alsa-utils. So try to configure alsa by running the command 'alsactl init' as root.
Just ignore the error message like 'Unknown hardware' (this issue said to be fixed
in alsa-utils .20), then reboot and try to test your sound.
For more details please see this thread.
だそうだよ。