This Is Your Brain on Music: The Science of a Human Obsession

by Daniel J. Levitin

When an instrument creates energy at frequencies that are integer multiples such as this, we say that the sound is harmonic, and we refer to the pattern of energy at different frequencies as the overtone series. There is evidence that the brain responds to such harmonic sounds with synchronous neural firings—the neurons in auditory cortex responding to each of the components of the sound synchronize their firing rates with one another, creating a neural basis for the coherence of these sounds. The brain is so attuned to the overtone series that if we encounter a sound that has all of the components except the fundamental, the brain fills it in for us in a phenomenon called restoration of the missing fundamental. A sound composed of energy at 100 Hz, 200 Hz, 300 Hz, 400 Hz, and 500 Hz is perceived as having a pitch of 100 Hz, its fundamental frequency.