There's a cool book that I'm reading right now that everyone should check out if you haven't already. It's called This Is Your Brain On Music. Very cool stuff. So far the most fascinating tidbit is that the neurons in your auditory cortex fire at the same rate per second as the vibrations of the tones that you hear. In other words if I play you an A 440, your neurons fire at 440 times a second. If I play you a note that vibrates 150 times a second they fire 150 times a second. Pretty wild stuff. Dig it.