Comment 2 for bug 795823

Thanks for your report. Please check that you have the appropriate capture device selected, and that the recording level is turned up. TO do so, click on the speaker icon in the top right hand corner of your screen, and choose "Sound Preferences". Select the Input tab, and select the audio input device, the input connector, and adjust the input volume. You can test to see whether your microphone is working by watching the graphical signal meter, located just below the volume control. If the computer is receiving audio as per your settings, then those bars should light up green.

Hope this helps.