It makes sense that we find either a steady tone or random noise uninteresting. Neither encodes information. If you accept a Darwinian point-of-view, our brains evolved to extract meaning out of sensory input from the environment. (Or, rather, individual organisms which were differentially better able to discriminate sights, smells, tastes and SOUNDS survived and reproduced in greater proportion and so passed along to the gene pool the DNA that enabled this ability.) However, it is difficult for me to see the adaptive survival value of music per se - unless it is related to social cohesion. Maybe those of our ancestors who enjoyed music found in it a reason to go on living.
I am curious about one thing. We are large brained social primates with a unique ability and drive to use language. Is there a neurological evolutionary connection between music and speech? Or is it just coincidental that all human societies world wide share both activities?