If you are met with a scratching sound (kind of noise) or close to clicking sound that Geiger counter produces, before doing anything else, check the volume level via (for example) alsamixer CLI application. After reboot of Ubuntu 9.04 runnig on my W500, I „magically“ got no sound at all, after fiddling with everything else (modules, checking BIOS, etc.) and thinking “… the OS remembers volume levels“ I found that the „PCM“ volume level was lowered to minium I wonder how did this happen.