I have been watching a number of HBO shows (Game of Thrones, Westworld, Watchmen, and The Plot Against America) on Sky Ticket in the last few years, and I noticed something curious about the "stinger" sound that plays together with the HBO logo at the very beginning of each episode.
In the Sky Ticket iPad app, the stream always starts off in the German dubbed version, and I have to manually switch it to English for almost every episode, since this setting is not remembered by the app. And since I do this at the very beginning of each episode, it almost always happens to coincide with the HBO logo.
And there I noticed something curious: when I switch languages, the pitch of the sound becomes lower, I think about a semitone. At first, I thought that maybe the note itself is dropping (similar to the logo stinger for Lost), and I am merely experiencing an auditory illusion due to the switch-over not being instantaneous.
But that is not the case. I played them side-by-side, and the English one really is about a semitone lower.
Another curious thing I noticed is that in either Game of Thrones or Westworld (I forgot which of the two), this stopped after a couple of seasons, where starting with one of the seasons, the pitch stayed the same when switching audio tracks.
I don't think PAL speedup is the reason, because a TV show would not originally have been shot at a cinema frame rate, but at a TV frame rate. Also, in at least one of the shows, the burnt-in subtitles are in German, not in English, indicating that it is the English audio track playing over the German video. Plus, when switching the audio track, no switching of the video stream is visible.
So, what is the reason? And why does it go away in later seasons of one show?