What a fabulous post,
Naturalist! I find it just so hard to articulate things because I'm a visual thinker... That's one reason my posts often end up quite long...just because I can't find the right words and feel I have to explain every little nuance in case others don't get it.
I think your idea about activating particular neuronal combinations is quite sound. (Oh, I think that could be a pun but it was unintended.
) And I would agree 100% that it's often those unexpected shifts within the song that provoke the most profound responses in me.
A good example of a song that consistently gives me ASMR is Prince's Adore, from the Sign O' The Times album. Now, I've never really been into such songs but my ex husband is a huge prince fan so I was exposed to his music. In the second verse after four lines (16 bars???) there is a change in the music and a cascading keyboard (no idea if this is the way to explain it, but it's a cascading melody) is introduced on the line, "They know we need each other..." And every time without fail it produces ASMR in me. Such a cheesy kind of song but I just kind of fell in love with how sweet it is and the colours it makes me see.