I have been having occasions lately where I’ll lose audio whilst using AirPlay mirroring from my Mac running OS X version 10.8.4 to my Apple TV running the latest Apple TV Software, version 5.3. When this issue occurs, audio from iTunes, Hulu, Netflix, etc. on the Apple TV plays audio normally, as does AirPlay content from an iOS device. It seems to be only OS X devices that are affected. Searches of Apple support forums and other places Mac nerds share information showed that this is not an issue peculiar to my equipment.
I have reported the issue to Apple, as I’m sure others have, and will continue to investigate on my own to see if I can uncover a specific cause and more finely tuned fix. In the meantime, forcing Core Audio on the Mac to restart seems to solve the problem, at least temporarily. Use the following command to stop Core Audio, which will then automatically restart.
sudo killall coreaudiod
I’ve also bundled this into an Automator application, if that makes things a bit easier for some. It will prompt for administrative credentials when launched.
Note: Restart coreaudiod is provided “as is” without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability, or fitness for a particular purpose.
The Mac Admin 
It works!!
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