How do I reset the default sound settings in Gnome?
 

While I was fumbling around trying to activate the build-in microphone of my webcam I seem to have changed my sound settings (but I don't know how) and now whenever I try to watch a video (in vlc, but I don't think it is specific to that only) I get a very annoying background noise and a kind of big hall echo. Can someone tell me how to return to the default sound settings of Gnome?

Try running Gmix (gnome-volume-control) and looking at the input sections.

You could also try running alsamixer and looking at the settings.

If Mint uses Pulse Audio as Ubuntu does, here's a link to the Pulse Audio help page.

Mint 9 Gnome uses PulseAudio, but I couldn't figure out what to do from the Help Page. I managed to reduce the noise by going to Menu>Preferences>Sound (Gmix, apparently) and at the Output tab setting the Connector to Analog Output/No Amplifier, but it still isn't as it should be...

In had a similar problem with Mint 10. I fixed it like this:

1. Boot from your original installation disk

2. Note the default sound settings (in my case in "sound mixer" and "alsamixer")

3. Reboot from hard drive

4. Transfer the settings