My Mac has no sound
Ok Here is the problem: Duolingo has no sound!
Try to see if other programs on your PC are silent. Try iTunes, or youtube.... If you have no sound the problem is IN YOUR COMPUTER
Solution: I just got off the Apple tech support and the solution he offered was this:
with your left hand hold SHIFT + CONTROL + OPTION
With your right hand tap the ON button
LET GO IMMEDIATELY (If you did this correctly your PC have NOT started) Now restart the computer.
What you just did was reset of the ummm "heart" that pumps electricity through your system. Chances are, your system had a fit and was not delivering enough power to your speakers. IT WORKED FOR ME!.... GOOD LUCK