I remember only two examples now. A hotel room in Bangkok, some enchanting Thai song coming from the radio hidden somewhere in the room as a quiet background music in the fascinating monotony of the night.
And a series of videos I have been sometimes watching since the last autumn -- all these videos have the same background music. It it barely audible and little by little begins to sound very enchanting, especially the ever-repeating series of high notes there; but once you put the earphones on to hear it better, you notice that it does not sound nearly as good: the low notes sound disturbing, cheap, though the high notes are almost as good as before.
So can the weak audibility sometimes be an essential part of music?
Sorry, it is morning and I go to bed, I have no time to proofread and check this message.