Just finished reading the 2006 book, This is Your Brain on Music, The Science of a Human Obsession by Daniel J. Levitin. No surprise that it was a finalist for the LA Times' Book Prize.
This wonderful book looks at music and the brain from a-to-z. In doing so, it demonstrates how music and modulated music travel about the brain in a way that influences our ability to trust, self-regulate, identify sounds in space, motor plan, communicate, organize, discriminate sounds, multi-task and relax. In other words, the book provides insight into how sound therapy works -- but without ever mentioning the term sound therapy.
Music operates independent from language. Some aspects of music, like pitch, are hard-wired into brain areas. They have their own neural centers on the right side of the brain. For example, a neuro-surgeon can pinpoint the note, C#, in the open brain. Other aspects of music: musical syntax, timbre, rhythm, etc., are processed simultaneously in their own specialized regions across the brain. Music can be an intellectual, regulatory, emotional and/or social experience. We admire the construction of a song, work to the beat of a driving rhythm, allow ourselves to move with musically expressed emotions, and make music a part of our social events and rituals.
The brain has two main pathways for music. The first moves from the inner ear into the auditory processing areas where it then moves to other high-functioning cortical regions including executive functioning and memory. The second pathway moves directly from the inner ear to the primitive cerebellum where motor planning and our fight-or-flight is centered. The cerebellum is also the seat of the brain's timing and rhythm, and has important emotional function. Both pathways are bi-connected to each other and to a variety of emotional centers in the brain including those responsible for pleasure and reward.
Why did music evolve into animals? Darwin linked music to sexual selection by virtue of music's seductive powers. Others have noted that it was (and continues to be) an important aspect of social bonding and cohesion. This would make it important to the evolution of social beings like ourselves.
The book is full of deep information as well as interesting tidbits.