Because it is rightly ordered beauty (most of it) and pleasing to the intellect. The intellect delights in that which is good, beautiful and true. Certain types

Because it is rightly ordered beauty (most of it) and pleasing to the intellect. The intellect delights in that which is good, beautiful and true. Certain types of music elicit a more base response, catering to the passions, such as EDM, or pop, tribal beats, etc. Other types of music cater to the intellect, such as classical, baroque, and certain types of folk and other genre's. Then you have sacred music, which is also prayer, such as gregorian chant and polyphony, these cause one to contemplate divine things. Music is pleasurable in all these facets because it touches upon different operations of the soul, which in turn gives pleasure to the body, such as calmness or dopamine, etc.