I think y’all are describing adrenlin boosts. The back of your head gets all tingling, you get mildly excited, and if it’s very strong it will continue down your back and spread through the entire head to your ears with goosebumps and raised hair following, and you feel like you’re ready to do 12 rounds with Mike Tyson. Yep. I know that one.
I get these at very defineable instances. Inspiring music, almost always. I got into music simply to keep replicating this feeling. A burst of inspiration during writing, fairly often, ending with a flurry of typing. And there’s runner’s high, which is a mild version.
Immediate danger also does the same thing, but it’s a different, faster kind of jolt, and not necessarily pleasant. The body is responding to circumstances, filling an order for quick, fast energy. I’m not sure why it does this for music, especially when I’m only listening, not playing an instrument, where there might be a need for sudden inspirational energy.
Also, very interesting - if I think of a particular song, storyline, or past memory, I can replicate the effect on command, and if I really concentrate, I can get an pretty impressive wave of tingling that rivals orgasm. Biofeedback?