Skype help! I can't hear them, they can hear me.?

I am trying to skype with a friend and they are able to hear me and I can not hear them. I have done chat with multiple people and I am sure they are talking because the blue ring around their profile picture lights up. I have tried echo123 and couldnt hear anything. When I go on audio setting (from the skype toolbar), the speakers appear to be working fine when people talk the green bar goes up and down however I still cant hear them... Any help would be appreciated