I dont think this is a pulseaudio bug. I actually have a similar bug with similar behavior but I decided to update the alsa stack and it fixed it.
https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1300844
Try updating sound as these instructions
https://wiki.ubuntu.com/Audio/UpgradingAlsa/DKMS
I dont think this is a pulseaudio bug. I actually have a similar bug with similar behavior but I decided to update the alsa stack and it fixed it.
https:/ /bugs.launchpad .net/ubuntu/ +source/ alsa-driver/ +bug/1300844
Try updating sound as these instructions
https:/ /wiki.ubuntu. com/Audio/ UpgradingAlsa/ DKMS