According to a recent Apple knowledge base article, some televisions and AV receivers may not handle audio playback from the latest-generation Apple TV properly. Although the Apple TV automatically detects and sets the proper audio playback settings for your setup, not all TVs work with these settings.
If you are experiencing a lack of sound after setting up your Apple TV, Apple suggests a few steps to confirm that your connections and settings are correct.
Of course you will want to be sure that your cables are all plugged in properly and your television's volume is turned on. If you are using audio from a receiver, be sure muting is not on and that you are on the proper input setting.
You can also change the audio output settings on your Apple TV:
- Be sure your Apple TV software is updated. Make sure your Apple TV is connected to the Internet; it should detect if there is a new update available.
- From your Apple TV, navigate to Settings > Audio & Video.
- Choose Audio Out and select the 16-bit option. Check your audio output to see if you can hear audio.