how to get audio to go to tv using mirroring from macbook pro

In System Preferences, Sound, select the AppleTV for output.

http://arstechnica.com/apple/2012/07/mountain-lion-airplay-mirroring-v-airparrot -fight/

That method does work, too, even if the "Mirroring" feature isn't supported on your machine.

Thanks for pointing it out!

YW

As it turns out, my external speakers right channel had failed. Audio and system alert sounds were "underwhelming" on the built-in iMac speakers but now play back clearly via the Apple TV over my shoulder.

You can also find audio mirroring options in iTunes (bottom right corner). But it doesn't send System sounds or anything that isn't playing directly in iTunes.

You can also Option-click the volume icon on your menubar to switch from internal speakers to AppleTV.

But I usually don't recommend this option because for some reason, some AppleTV's fail to show up there.

Tested and confirmed.

My Apple TV showed up with the "option key click" on the Volume icon in the Menu bar. Beats the extra steps of System Preferences, too.