Click here to skip to the howto section. It's funny how it was basically the exact same problem that I ran into in Ubuntu 11.04 (Natty Narwhale) that put me on the correct path to resolve this issue. Basically, to sum up, this problem affects a number of modern laptops that have dual-channel internal microphones, which (apparently) are intended to support dual channel audio recording. Exactly how two microphone channels on either side of your laptop are going to produce anything remotely near to the quality of two microphones is beyond me, but in this case it causes special issues that need to be addressed in LINUX.
I like to create videos of my desktop and various other things, and occasionally even use the YouTube webcam recorder. Even more occasionally I'll take advantage of Google Talk's built-in video chat. Nothing drives me crazier than something that I occasionally use not working and costing me stupid amounts of time trying to resolve, so I've started categorizing this issue as a high-priority item to resolve just to get it out of the way before I need it.
After installing #!, I noticed that I was not getting any microphone response on the YouTube webcam recorder, and initially attempted to resolve it using the GUI mixer by right-clicking on the volume control icon and selecting "mixer". I then activated the microphone by clicking the red X next to the speaker icon and, when that didn't help, I clicked on the chain icon and lowered the right channel volume to 0, leaving the left channel volume set to maximum. This still didn't help, so I selected the Capture tab, clicked on the gray dot beneath the first Capture entry, and when this did not resolve the problem I set it aside for the time being.
Because these sorts of issues tend to fester in my brain, I took another couple cracks at it before finally applying myself to focusing on the issue in alsamixer like I had before. In my experience, solutions tend to be more likely and also tend to stick when using terminal (or in this case terminator).
Again, in alsamixer I had the right channel of the microphone reduced to 0 volume, and the left channel set to 100, as this is what had solved my problems in Ubuntu. This didn't help me here. I then experimented with various settings, but finally came up with this as the final solution:

I arrived at this solution after pressing F1 to read the Help dialogue, and noticed that while Capture was selected, I could press the Spacebar to toggle Capture on and off (it shows up red in the above screenshot). More importantly, I noticed that if I pressed either the ; or ' keys I would toggle the left or right capture channel off and on. I toggled the right channel to off with the ' key and left the left channel enabled, then tried again. Success! In this case it appears that the left and right microphone channels compete with each other for the same resources, effectively cancelling each other out. Disabling one allows the other to work. Since I have no plans for recording dual channel audio with my internal laptop microphone, this solution works just fine. YouTube and Record My Desktop work great now.
I still need to work out how to resolve issues with Google+ Hangouts / Google Talk, but that's not a priority for me at the moment. See below for step by step instructions including support for Google+ Hangouts / Google Talk video chat / Google Voice.
Instructions:
Open a terminal window and type the following to open the mixer:
Make sure you have the correct sound card selected. In my case it was the default sound card, but you can press F6 and use the arrow keys to select the one you want from the small window that pops up in the alsamixer, or the Esc key to leave the window and return to the mixer. See the included screenshot above for reference.
Press F5 to view all devices - typically they will not all fit on a default size terminal window, but you can extend the window or maximize it so you can view everything on one screen if you so wish. Alternately you can use your right and left arrow keys to move between each section as you jump from device to device.
Use the right and left arrow keys to navigate to Mic. If you see MM at the bottom of the volume indicator, that means the microphone is muted, otherwise it should display 00. Press the M key on your keyboard to toggle to unmuted if it is not already displaying 00. Also use the up and down arrow keys to change the volume, I recommend setting it to 100 with the up arrow key.
Now use the right or left arrow key to select Mic Boost (there may be two entries) and lower the volume (on each) to 0. Mic Boost is likely to cause problems by creating distortion and noise interference - only if you find your recording volume is too low should you raise the volume on these devices.
Verify that Input source is set to the correct device. In my case, Input Source is set to Internal Mic, and Input Source 1 is set to Mic (to allow me to hook up an external microphone if I so choose). To change either, use the left or right arrow keys to select each device, then while selected use the up and down arrow keys to select your preferred option.
Next, select Capture using the left or right arrow key. Raise the volume to 100. If you do not see the word CAPTURE in capital red letters, press the Space bar to toggle it enabled. If your system is a laptop equipped with dual channel audio, press either the ; or the ' key to toggle either the left or the right channel disabled (only one needs to be disabled). If this does not work, you may need disable CAPTURE on this device, and enable it on Capture1 or Digital (sometimes these entries are not labeled correctly and some trial and error may be necessary to determine which one matches your audio card's microphone).
Press the Esc key to quit out of the alsamixer. This would be a good time to test audio recording using something like RecordmyDesktop or YouTube's web camera recorder. YouTube's web camera recorder is particularly helpful because it will display microphone activity even if you are not recording.
If you intend to use Google Talk's video chat, Google Voice or Google+ Hangouts you will need to do the following. If you have already installed the GoogleTalk Plugin skip down to the enxt step. Download the GoogleTalk Plugin here: http://www.google.com/chat/voice/ and select the correct .deb file for your system (32-bit or 64-bit). Install it with Gdebi Package Installer by right-clicking the downloaded file in the File Manager and selecting this option. Enter your password when prompted and allow the install to complete.
Enter the following commands into your terminal window:
|
cd ~/.config/google-googletalkplugin
cp options options.bak #there may be no options file yet
nano options
|
Look the following entry (if you are creating a new options file or this entry is not present skip to the next step):
And change it to the following (or simply add this line if it is not in the options file):
Then press CTRL+X to Exit, and save your changes when prompted by pressing the Y key. Enter the following into your terminal window to return to your home directory:
Now you need to figure out the hardware name of your microphone by typing this command:
This should generate something that looks like the following:
|
card 0: Intel [HDA Intel], device 0: ALC60 Analog [ALC670 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
|
In my case, the device name I was looking for was to the right of card 0: - Intel. Now it's time to create an .asoundrc file if you don't already have one.
Add the following into your new .asoundrc file (if you already have a .asoundrc file you may wish to copy your file to something like .asoundrc-old first as a backup):
|
pcm.internal #named for internal mic, could be pcm.anything
{
type hw
card Intel #Change the name of your card here as appropriate
playback.pcm
}
pcm.!default
{
type asym
playback.pcm
{
type plug
slave.pcm "dmix"
}
capture.pcm
{
type plug
slave.pcm "internal" #must match the name selected on the first line after 'pcm.'
}
}
|
Click CTRL+X to Exit, and save when prompted by pressing the Y key. Reload ALSA by typing the following:
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sudo service alsa-utils restart
|
You should now be able to use your microphone via the Google Talk plugin in Google Talk, Google Voice or Google+ Hangouts. Because Skype is now owned by Microsoft, please don't ask me to help you with your Skype issues - however, the above should help get you working.