Detects noise, doesnt play it

When I'm in a chatroom, everything works fine, according to what my computer detects. My friend can hear me when I talk, and the blue light next to my name flashes when he talks, the issue is that when it flashes for him talking, I cannot hear anything. The test sounds work, but real chat sounds dont.

2010 macbook pro 17"
running yosemite

Detects noise, doesnt play it