Brian Greene: Well, all sounds—all music in particular—comes from vibrations. So the reason why you can hear me speak is because I am creating pressure waves that are emanating from my mouth, compressing the air, then rarifies as it spreads out, compresses again. And that ripple of air ultimately bangs into your eardrum, smashes your eardrum with these molecules of air, going back and forth and your eardrum registers and your brain decodes that. And you have the sensation of hearing. So all sound is a matter of producing those pressure waves, those vibrations in air.