Only developers have access to the speaker-out function so far but iOS 6 will be released to the public later this year. A few developers have let us know that the feature is working and is fully functional in the latest beta 3 of iOS 6 for the Apple TV box.
The AirPlay speaker-out function can be found in the AirPlay menu on Apple TV. From here you can select all your AirPlay speakers in your home. The Dolby setting option in the audio has to be turned off. Otherwise, sound volume is very low, it is said.
Apple will release iOS 6 to the public this fall.
Read More [via AppleInsider]