Probably not terribly related, but I wonder if it might someday be possible to hook up an EEG to your brain while supervised (user preferences feedback) machine learning plays through a variety of music and records your brain activity, and from that discover music or simple obscure rhythmic sounds that happen to be particularly pleasing in various ways to an individual.
https://www.derivative.ca/events/2016/ThoughtForms/
What do the thoughtforms represent? The abstract shapes on the screen change and respond to your thoughts to detect calm, attention, excitement, anxiety and focus.
https://en.wikipedia.org/wiki/Electroencephalography