If your not able to hear audio while watching videos in Chrome then try this:
1) Open Chrome and type “chrome://plugins/” without the double quotes into the address bar
2) Disable the built-in Chrome Adobe Flash Player
3) Download and install Adobe Flash Player for Google Chrome (Mac version) from here: http://get.adobe.com/flashplayer/?fpchrome
4) Restart Chrome
NOTE: If restarting Chrome doesn’t fix the problem try rebooting your mac.
Hope this helps.