I have Skype version 18.104.22.168 on Ubuntu 12.04 I have tested my webcam and video and audio are working. On Skype my vid and audio work going OUT but I get no sound coming IN. In the sound options my speakers are set to "PulseAudio server (local)" and there is no other option. When I watch the PulseAudio Volume Control display (Output Devices) I see that I AM getting audio from Skype but it's not getting to my speakers. ???? Skype does make all the usual noises e.g. when someone is calling etc.
First check if your mic is working properly. You can do