Like everyone else stated, I believe this is a wireless network issue. This type of thing is not just limited to Apple TV - it affects everything. I have know somebody with an Oppo bluray player and external antenna. He would get audio drop-outs from his computer server unless the antenna was positioned "just so". A hard-wired internet connection using an ethernet cable to your internet router will always be superior. An upgraded wireless router with multiple antenna arrays may also help.
Most likely the reason why there isn't a drop-out when viewing streaming movies is that the client streaming app will download and cache movie data. If there is an internet interruption, it has already cached a certain amount of movie time within the device.
Most likely the reason why there isn't a drop-out when viewing streaming movies is that the client streaming app will download and cache movie data. If there is an internet interruption, it has already cached a certain amount of movie time within the device.