Under 13.06, on the same computer, my C170 webcam works perfectly with Skype. Under 13.12 the sound was initially missing. After some twiddling with Phonon in System Settings the Input Levels slider is permanaently at halfway and if I call the Skype voice test I get a loud buzz, which won’t go away until I log out and in.
How do I fix this?
[color=#000080][i]Use Netrunner 13.12 64 bit.
I had some sound problems when someone is connected or disconnected in Skype, making an annoying noise, I solved completely removing and installing Skype version for 32 bit, the webcam, the microphone and speakers work perfect now and no annoying noises when someone connects or disconnects.[/i][/color] 
Try fix below…worked for me. I also had the Buzz problem and more.
http://forums.netrunner-os.com/showthread.php?tid=2424&pid=4586#pid4586
I uninstalled and reinstalled Skype, and applied the “load-module module-udev-detect tsched=0” fix, but the only difference is that the Skype sound test plays back white noise instead of a buzz. The Phonon sound level is now behaving sensibly, but this does not help Skype. I have tried switching from VLC to Gstreamer, but it makes no difference.
Phonon has a Test function which is fine for Video but I don’t see how it works for audio. I’ve tried “prefer” on the webcam but that doesn’t help either.
Further experimentation suggests that Skype is not connecting to the webcam, as the webcam light does not come on when Skype is used, and neither audio nor video is transmitted. When in the Phonon window of System Settings the light does come on and the volume indicator shows sound is being picked up, and the video test shows the video works. I have tried running Skype while the Phonon window is causing the webcam light to come on, but to no effect.
How do I get Skype to use the webcam?
[attachment=120]Solution found! Eventually.
After some Googling I tried a variety of tricks using LD_PRELOAD=/usr/lib/i386-linux-gnu/libv4l/v4l1compat.so, which had no effect. I ended up at https://help.ubuntu.com/community/SkypeTroubleshooting where I found the answer.
Install pavucontrol (Pulse Audio Volume Controller).
In Pulse Audio Volume Controller, with the Recording tab visible, make the Skype test call, or any other call. While the call is in progress you will be able to select your webcam, in my case, C170 Analogue Mono, see attachment, from the selection, which will permanently connect Skype to the webcam, both audio and video.