I ran "apt-get upgrade" on my 12.04 system and the USB webcam mic stopped working. It had previously worked for several years under several different Ubuntu versions. I noticed from the apt logs that this upgrade updated everything in the sound system (linux-sound-base, pulseaudio, etc).
After the update the mic is detected and appears in the list of sound cards and appears in pulse audio, but it only works for perhaps a minute after the system boots. Then it freezes with a fixed (low, but nonzero) input level. If I go into pavucontrol and turn the device off and then back on then it works again for another minute.
I tried a second USB mic and it exhibits the same behavior. Both devices are Logitech.
I tried these devices under 13.04 on a different system and they both exhibit the same behavior there.
From what I gather, rolling back an update is not easy. Is there anything else I can do to get these devices working?