This is your brain, this is your brain on Chopin. The NYTimes Science section has a lengthy and fascinating feature on how and why we respond to certain qualities of music — not just rhythm or melody but even subtle interpretations of the exact same song.
Research is showing, for example, that our brains understand music not only as emotional diversion, but also as a form of motion and activity. The same areas of the brain that activate when we swing a golf club or sign our name also engage when we hear expressive moments in music. Brain regions associated with empathy are activated, too, even for listeners who are not musicians.
And what really communicates emotion may not be melody or rhythm, but moments when musicians make subtle changes to the those musical patterns.
Even non-musicians can distinguish between, say, different versions of the same Mozart piano concerto. The timing of the notes is more important than loudness or softness when it comes to conveying emotion, and we tend to enjoy music with rhythms close to our own body rhythms (jogging, for instance).
Musicians like [Paul] Simon consider slight timing variations so crucial that they eschew the drum machines commonly used in recordings. Dr. Levitin says Stevie Wonder uses a drum machine because it has so many percussion voices, but inserts human-inflected alterations, essentially mistakes, so beats do not always line up perfectly.
And Geoff Emerick, a recording engineer for the Beatles, said: “Often when we were recording some of those Beatles rhythm tracks, there might be an error incorporated, and you would say, ‘That error sounds rather good,’ and we would actually elaborate on that.
“When everything is perfectly in time, the ear or mind tends to ignore it, much like a clock ticking in your bedroom — after a while you don’t hear it.”