I've been reading Music, the Brain, and Ecstasy, by Robert Jourdain, and it's been excellent. It discusses music and our perception of it in several parts. He first discusses it as sound, then breaks the sounds down into tones, our musical building blocks. He shows how tones are built into melodies, and how melodies are arranged with rhythm.

Jourdain next discusses the composition, performance, listening and understanding of music by immersing the reader in the cognitive processes involved in each. I've found the topic of composition really interesting. I'm an aspiring composer and I'm eating up his descriptions of the composing habits of Schubart, who heard a constant stream of original music in his head, and Beethoven, a composer of deep structure who wrote all of his music in score, even pasting the pages of his notebook on the wall to see it all continuously. Jourdain finishes the book by exploring the ecstasy we feel when we listen to beautiful music.

It's a scientific and informative book, written with the luscious fluidity of poetry. Jourdain is a great writer.

Here's a list of other book on music cognition that might interest you. I'm personally trying to find a copy of "The War of Art".