Volume swings happen only when watching video.    



From ArsTechnica:

At first, I thought my mind was going. My wife and I, on vacation recently, had just settled in with an episode from the final season of 30 Rock. I had purchased it from Amazon Instant Video for a couple of bucks because Netflix didn't have the final season yet, and if there is one guaranteed benefit to not being a dirty pirate, it's studio-quality audio and video, right?

Imagine my surprise, then, when the volume began subtly modulating. For 30 seconds, Alec Baldwin and Tina Fey were shouting at me; for 30 seconds, they were whispering. Well, crazy things happen; perhaps the version of the episode shipped over to Amazon had been mastered poorly by some summer intern.

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