Izzy Restful

Im having probelms with my voice, its not letting me hear people or talk which is pretty annoying

I recently got a MAC computer when i intsalled SL my voice wont work, I already tried to disable and enable it again and restart sl. I even installed a new veiwer and im still having the same problem! When i was on a windows computer I didn't have this issue does anyone know what I can do?! Thank you in advance please help!