USB webcam microphone not working

Based on the output of pacmd list-sources, all of your microphones are suspended for being idle (which makes sense). What I have found with some USB-connected devices is that once the microphone is set to SUSPENDED they never come back. There are generally two solutions for this problem:

1. Unplug the webcam, count to five, and plug it back in.
   ⇢ This will cycle the USB device and generally brings all of the devices back online.
2. Update PulseAudio to not suspend idle audio devices.
   ⇢ This has generally worked well for a number of computers at work where the USB cameras cannot be physically disconnected from the computer without a sharp pair of scissors.

Modifying PulseAudio

To prevent audio devices from being suspended when idle, you will need to comment out a single line in the default.pa file. These are the steps to follow:

0. Open Terminal (if it's not already open)

1. Open the default.pa file for editing as root:

   $ sudo vi /etc/pulse/default.pa
   

   Note: Feel free to use something other than vi. This is more a force of habit than an implicit recommendation for which editor to use.

2. Find the line that reads load-module module-suspend-on-idle and comment it out. This will be about 90% of the way down. Once done, the line should look like this:

   ### Automatically suspend sinks/sources that become idle for too long
   # load-module module-suspend-on-idle
   

3. Restart PulseAudio:

   $ pulseaudio -k
   

4. Confirm your audio devices are operational:

   pacmd list-sources
   

   Check for the USB microphone, which may be at index 0 like it is in the output you provided, and confirm the value of state. It should read IDLE. When this is being actively used by an application it will change to RUNNING, then go back to IDLE about 30 seconds after it is no longer in use.

Audio Confusion

One additional issue you might see is that an application may not know which microphone to use automatically and, as a result, the input selection will always be empty. To resolve this, open the PulseAudio Volume Control (pavucontrol) application and click on the "Configuration" tab. Set the output to "Analogue Stereo Output":

Why setting the output resolves an issue with input, I can only guess at. That said, this solution does work for those rare instances when the computer consistently shows no audio input device.