Recently, I had trouble getting my microphone to work in Ubuntu 7.04 Feisty Fawn. I need it for Skype. Tried lots of things and searched Google a lot for answers.
Finally, I think what really fixed it was following the instructions on this page to update to the most recent version of alsa.
My microphone works now. Here are my settings after updating to the latest alsa:
To see the desktop sound settings, click on the sound icon at the top right of your desktop. I have three tabs, they say, "Play Back", "Recording", and "Options". In Play Back and Recording the sound is turned all the way up. In options I have "Front Mic" selected as the Input Source. This is so that I can plug in my microphone into the microphone slot/jack in the front of my computer.
Open up a console. Type in alsamixer and press enter. I turned up the volume in every setting I could in that application by pressing the up key for each setting. Make sure that none of the settings are muted. I think the microphone option is muted by default. To unmute, go to one of the settings and press the m key. On my machine when I do that, I get "00" at the bottom of the setting. The "00" means that the option/setting is unmuted. To move around in the settings use the arrow keys. To move to more options, press the tab key. Go to the setting called "ADCMux". Then press the space bar. This make the word "CAPTUR" appear. Now you're done. Press escape to get out. Go to options in Skype and choose the Sound Devices option. Test the microphone and sound there.
20 November 2008
Also make sure that "Analog Mix" is enabled in the Volume Control. If your microphone is analog then it won't work until you un-mute Analog Mix and turn up the volume