Apple is researching how a future iPhone can save power by automatically pausing playback when you're not paying attention to media."In another example, user motion is recognized as an indication of interest based on its type (e.g., corresponding to excited behavior)," continues Apple, "and/or the movement following shortly after the time at which a significant event, e.g., a touchdown, occurs in the audio."But the patent application also covers detection of external audio, such as when you may be dancing in the street.That's partly about whether your attention is away from whatever else your phone is doing, but perhaps mostly because of checking for context.It surely couldn't be enough to tell the iPhone you're on the N, Q, R or W.Yet if the iPhone identifies the sound of train tracks, and you keep bopping even between the different kind of tracks that Taylor Swift makes, it all helps build up a picture of what you're concentrating on."