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

by Daniel J. Levitin

Music listening, performance, and composition engage nearly every area of the brain that we have so far identified, and involve nearly every neural subsystem.

The Catholic Church banned music that contained polyphony (more than one musical part playing at a time), fearing that it would cause people to doubt the unity of God. The church also banned the musical interval of an augmented fourth, the distance between C and F-sharp and also known as a tritone (the interval in Leonard Bernstein’s West Side Story when Tony sings the name “Maria”). This interval was considered so dissonant that it must have been the work of Lucifer, and so the church named it Diabolus in musica.

As the composer Edgard Varèse famously defined it, “Music is organized sound.”

The basic elements of any sound are loudness, pitch, contour, duration (or rhythm), tempo, timbre, spatial location, and reverberation.

Pitch is a purely psychological construct, related both to the actual frequency of a particular tone and to its relative position in the musical scale. It provides the answer to the question “What note is that?” (“It’s a C-sharp.”) I’ll define frequency and musical scale below.

Reverberation refers to the perception of how distant the source is from us in combination with how large a room or hall the music is in; often referred to as “echo” by laypeople, it is the quality that distinguishes the spaciousness of singing in a large concert hall from the sound of singing in your shower. It has an underappreciated role in communicating emotion and creating an overall pleasing sound.

It might seem as though we should simply say that pitch is the same as frequency; that is, the frequency of vibration of air molecules. This is almost true. Mapping the physical world onto the mental world is seldom so straightforward, as we’ll see later. However, for most musical sounds, pitch and frequency are closely related.

The lowest note on a standard piano vibrates with a frequency of 27.5 Hz.

Sounds with frequencies above the highest note on the piano keyboard, around 6000 Hz and more, sound like a high-pitched whistling to most people. Above 20,000 Hz most humans don’t hear a thing, and by the age of sixty, most adults can’t hear much above 15,000 Hz or so due to a stiffening of the hair cells in the inner ear. So when we talk about the range of musical notes, or that restricted part of the piano keyboard that conveys the strongest sense of pitch, we are talking about roughly three quarters of the notes on the piano keyboard, between about 55 Hz and 2000 Hz.

The piano has the largest range of any instrument,

Pitch is so important that the brain represents it directly; unlike almost any other musical attribute, we could place electrodes in the brain and be able to determine what pitches were being played to a person just by looking at the brain activity.

This direct mapping of pitch is so important, it bears repeating. If I put electrodes in your visual cortex (the part of the brain at the back of the head, concerned with seeing), and I then showed you a red tomato, there is no group of neurons that will cause my electrodes to turn red. But if I put electrodes in your auditory cortex and play a pure tone in your ears at 440 Hz, there are neurons in your auditory cortex that will fire at precisely that frequency, causing the electrode to emit electrical activity at 440 Hz—for pitch, what goes into the ear comes out of the brain!

The most common subset of seven tones used in Western music is called the major scale, or Ionian mode (reflecting its ancient Greek origins). Like all scales, it can start on any of the twelve notes, and what defines the major scale is the specific pattern or distance relationship between each note and its successive note. In any major scale, the pattern of intervals—pitch distances between successive keys—is: whole step, whole step, half step, whole step, whole step, whole step, half step. Starting on C, the major scale notes are C - D - E - F - G - A - B - C, all white notes on the piano keyboard. All other major scales require one or more black notes to maintain the required whole step/half step pattern. The starting pitch is also called the tonic of the scale. The particular placement of the two half steps in the sequence of the major is crucial; it is not only what defines the major scale and distinguishes it from other scales, but it is an important ingredient in musical expectations. Experiments have shown that young children, as well as adults, are better able to learn and memorize melodies that are drawn from scales that contain unequal distances such as this. The presence of the two half steps, and their particular positions, orient the experienced, acculturated listener to where we are in the scale.

When I was in graduate school, my advisor, Mike Posner, told me about the work of a graduate student in biology, Petr Janata. Although he hadn’t been raised in San Francisco like me, Petr had long bushy hair that he wore in a ponytail, played jazz and rock piano, and dressed in tie-dye: a true kindred spirit. Peter placed electrodes in the inferior colliculus of the barn owl, part of its auditory system. Then, he played the owls a version of Strauss’s “The Blue Danube Waltz” made up of tones from which the fundamental frequency had been removed. Petr hypothesized that if the missing fundamental is restored at early levels of auditory processing, neurons in the owl’s inferior colliculus should fire at the rate of the missing fundamental. This was exactly what he found. And because the electrodes put out a small electrical signal with each firing—and because the firing rate is the same as a frequency of firing (as we saw above)—Petr sent the output of these electrodes to a small amplifier, and played back the sound of the owl’s neurons through a loudspeaker. What he heard was astonishing; the melody of “The Blue Danube Waltz” sang clearly from the loudspeakers: ba da da da da, deet deet, deet deet. We were hearing the firing rates of the neurons and they were identical to the frequency of the missing fundamental. The overtone series had an instantiation not just in the early levels of auditory processing, but in a completely different species.

Clarinets, for example, are characterized by having relatively high amounts of energy in the odd harmonics—three times, five times, and seven times the multiples of the fundamental frequency, etc. (This is a consequence of their being a tube that is closed at one end and open at the other.) Trumpets are characterized by having relatively even amounts of energy in both the odd and the even harmonics (like the clarinet, the trumpet is also closed at one end and open at the other, but the mouthpiece and bell are designed to smooth out the harmonic series). A violin that is bowed in the center will yield mostly odd harmonics and accordingly can sound similar to a clarinet. But bowing one third of the way down the instrument emphasizes the third harmonic and its multiples: the sixth, the ninth, the twelfth, etc.

This new technique became known as frequency modulation synthesis, or FM synthesis, and became embedded first in the Yamaha DX9 and DX7 line of synthesizers, which revolutionized the music industry from the moment of their introduction in 1983. FM synthesis democratized music synthesis. Before FM, synthesizers were expensive, clunky, and hard to control. Creating new sounds took a great deal of time, experimentation, and know-how. But with FM, any musician could obtain a convincing instrumental sound at the touch of a button. Songwriters and composers who could not afford to hire a horn section or an orchestra could now play around with these textures and sounds. Composers and orchestrators could test out arrangements before taking the time of an entire orchestra to see what worked and what didn’t. New Wave bands like the Cars and the Pretenders, as well as mainstream artists like Stevie Wonder, Hall and Oates, and Phil Collins, started to use FM synthesis widely in their recordings. A lot of what we think of as “the eighties sound” in popular music owes its distinctiveness to the particular sound of FM synthesis.

The word beat indicates the basic unit of measurement in a musical piece; this is also called the tactus.

A majority of people in our study—nonmusicians—were able to sing songs within 4 percent of their nominal tempo.

We are also under the illusion that we simply open our eyes and—we see. A bird chirps outside the window and we instantly hear. Sensory perception creates mental images in our minds—representations of the world outside our heads—so quickly and seamlessly that it seems there is nothing to it. This is an illusion. Our perceptions are the end product of a long chain of neural events that give us the illusion of an instantaneous image. There are many domains in which our strongest intuitions mislead us. The flat earth is one example. The intuition that our senses give us an undistorted view of the world is another.

Findings like these have led researchers to conclude that memory is not particularly accurate, and that it is constructed out of disparate pieces that may themselves not be accurate. Memory retrieval (and perhaps storage) undergoes a process similar to perceptual completion or filling in.

Wittgenstein proposed that category membership is determined not by a definition, but by family resemblance. We call something a game if it resembles other things we have previously called games. If we go to the Wittgenstein family reunion, we might find that certain features are shared by members of the family, but that there is no single physical feature that one absolutely, positively must have to be a family member.

There are three basic appearance-reality problems that need to be solved by all higher animals, he says. In order to survive, to find edible food, water, shelter, to escape predators, and to mate, the organism must deal with three scenarios.

Scientists call these ear worms, from the German Ohrwurm, or simply the stuck song syndrome.

The cerebellum has traditionally been thought of as that part of the brain that guides movement. Most movements made by most animals have a repetitive, oscillatory quality. When we walk or run, we tend to do so at a more or less constant pace; our body settles into a gait and we maintain it. When fish swim or birds fly, they tend to flip their fins or flap their wings at a more or less constant rate. The cerebellum is involved in maintaining this rate, or gait. One of the hallmarks of Parkinson’s disease is difficulty walking, and we now know that cerebellar degeneration accompanies this disease.

One solution to the binding problem, Crick proposed, was the synchronous firing of neurons throughout the cortex. Part of the “astonishing hypothesis” of Crick’s book was that consciousness emerges from the synchronous firing, at 40 Hz, of neurons in the brain.

Avram Goldstein had shown in 1980 that the pleasure of music listening could be blocked by administering the drug nalaxone, believed to interfere with dopamine in the nucleus accumbens.

Finally, a network of regions—the mesolimbic system—involved in arousal, pleasure, and the transmission of opioids and the production of dopamine, culminating in activation in the nucleus accumbens. And the cerebellum and basal ganglia were active throughout, presumably supporting the processing of rhythm and meter. The rewarding and reinforcing aspects of listening to music seem, then, to be mediated by increasing dopamine levels in the nucleus accumbens, and by the cerebellum’s contribution to regulating emotion through its connections to the frontal lobe and the limbic system. Current neuropsychological theories associate positive mood and affect with increased dopamine levels, one of the reasons that many of the newer antidepressants act on the dopaminergic system. Music is clearly a means for improving people’s moods. Now we think we know why.

Music, according to Sperber, developed parasitically to exploit this capacity that had evolved for true communication. Ian Cross of Cambridge University sums up: “For Pinker, Sperber, and Barrow, music exists simply because of the pleasure that it affords; its basis is purely hedonic.”

This may account for why, according to a recent European study, 10 percent of mothers reported that their children were being raised by men who falsely believed the children were their own.