Okay, well I'll just add that vitamins seem to enchance it. Specifically ones that are good for blood circulation. Cutting out grease seems to help as well. Same with sugar, ect...
The other day, I was able to put headphones over my temples and I could feel the tingles like crazy. I couldn't hear the sound at all. It's like I could feel the soundwaves or magnetism interacting with my brain.
Does that help? In any event, it doesn't seem to be autonomous. Or perhaps it is as it might be unique to each individual. Not sure how autonomy plays a role in it.
Certain videos are just better at triggering it, but once it gets going, I noticed I could get nearly every video to trigger it.
The really crazy part about it, which might add some credence to chakra religions, is that I can get the ASMR response in different areas of my body all things depending. Without knowing a single thing about chakras, and reading up on it, the ASMR "vibrations/tingles/chills" seem to correlate with descriptions of chakras.