PhD in neuroscience here. I didn’t specifically study musicology, but i did study the neuroscience of music.

The theory that holds the most water, in my opinion, is that music activates all the same parts of the brain as motor processing. It makes us want to move, and to make predictions about what’s coming next. People like makimg predictions. It’s also a pro-social activity that encourages bonding and communication. These are typically positive experiences.