Microphone Not Working on Skype

I believe there might be various reason why microphone not working correctly under Skype for Ubuntu. For my case, my laptop is Lenovo Y500 (with dual GT650M), and ubuntu version 14.04 64-bit. From what I read from various forum, the problem happen because Pulseaudio from ubuntu assumed that the laptop comes with stereo mic, but the real case is that some laptop only comes with single mic (forums say that this problem will not happen for laptop with stereo mic, but I am not too sure about this). Somehow both left and right mic will cancel out each other in Pulseaudio causing no sound being received by Pulseaudio.

One way around this, which is working for me is to install PulseAudio Volume Control, and mute one side of the mic volume.

1. Install PulseAudio Volume Control from Ubuntu Software Center. Search for PulseAudio Volume Control and click Install.

2. Set one channel of the mic to 0% and another channel to 50%. Run PulseAudio Volume Control by searching it from Unity Dash. Jump to the 4th tab (Input Devices), click the top right Lock icon to unlock the left and right channel "lock" and turn the volume of one channel to 0%, and another channel to around 50%. The lock Icon on the top right will lock the volume adjustment of the left and right channel together, make sure it is unlocked.

3. Disable Skype to automatically adjust mixer levels. Go to the setting of Skype, under Sound Devices, uncheck the "Allow Skype to automatically adjust my mixer levels". Having this checked will somehow cause the volume to be increase and decrease which will lead to the same volume level for both left and right channel.

Also remember not to adjust the volume of the mic level from sound setting. If you need to edit the level of the mic, you will need to go back to the PulseAudio Volume Control. Adjusting the mic level from Sound setting will also lead to same level for both left and right channel.

4. Verify the functionality of the mic on Skype. Finally, test out the functionality of the mic by running the test call services.