Why you can’t get that song out of your head

LISTENING to music has long been heralded as a gateway to the mystical, a relatively cheap and easy transcendent experience. Subjecting this magical and intimate pursuit to scientific inquiry can seem reductive or even clueless, at least to some among the aesthetically minded. One school of thought in neuroscience actually deems music unworthy of serious study, dismissing it as a sort of cerebral indulgence or audio cheesecake. Author Daniel J. Levitin challenges these perceptions in “This Is Your Brain on Music.”

Levitin, a professor of cognitive psychology at McGill University in Montreal, insists that appreciation of music and dedication to science go hand in hand, citing his pre-academic background as a musician, recording engineer and record producer by way of example. At the same time, he explores philosophical questions raised by his research on music and the brain, even offering a matter-of-fact solution to Irish philosopher George Berkeley’s famous conundrum: If a tree falls in a forest and no one is there to hear it, does it make a sound? “Simply, no,” Levitin writes. “[S]ound is a mental image created by the brain in response to vibrating molecules.”

Think about that for a minute. What comes through our eardrums when we hear music are vibrations, flutters and fluctuations around a tiny membrane in our ear. “Sound waves impinge on the eardrums and pinnae (the fleshy parts of your ear),” Levitin notes, “setting off a chain of mechanical and neurochemical events” whose end product is “an internal mental image that we call pitch.” That means “there can be no pitch without a human or animal present. A suitable measuring device can register the frequency made by the tree falling, but it is not pitch unless and until it is heard.”

So although we create a kind of internal music as we perceive sounds in the world around us, we don’t really “hear” this music in our heads. Instead it’s a neurological simulation, a mirror image drawn largely from the multilayered workings of memory. And unlike the fastest computer microprocessor, our brain performs its myriad tasks simultaneously.

Levitin is a deft and patient explainer of the basics for the non-scientist as well as the non-musician. This reader sighed with relief when the author paused to remind me that neurons are the primary cells of the brain and synapses are spaces between neurons and when he underscored how clusters of neurons form specialized networks in the brain. Aimed squarely at the general reader, “This Is Your Brain on Music” successfully unravels some of that long chain of neural events without getting tangled up in it.

Perhaps Levitin’s most fundamental and surprising observation is how much we know intuitively about music, its structures, forms and logic. We can recognize a song’s chords -- in the absence of its melody -- because they’re familiar groupings of notes (or pitches) ordered in a familiar pattern, following a path (or scale) guided by a key (or fundamental) note.

Levitin points out that the Eagles “don’t have to play more than three chords before thousands of non-musician fans in the audience know they are going to play ‘Hotel California.’ And even as they have changed the instrumentation over the years, from electric to acoustic guitars, from twelve-string to six-string guitars, people recognize those chords; we even recognize them when they’re played by an orchestra ... in a Muzak version in the dentist’s office.”

Even those who can’t find middle C on a piano and aren’t Eagles fans somehow can sense what should come next. The reason, Levitin says, is that “[n]etworks of neurons ... form abstract representations of musical structure and musical rules, something that they do automatically and without our conscious awareness.”

Levitin’s research occurs at the intersection of neurology (brain science) and psychology (mind study). By his own admission, he’s more of a mind guy than a brain dude. Yet its necessary focus on laboratory experiments renders his book far more controlled and clinical in the telling than, say, Oliver Sacks’ elegant, evocative case histories. In the absence of a unifying theory as in Malcolm Gladwell’s “Tipping Point” or a conceptual hook as in “Freakonomics” by Steven D. Levitt and Stephen J. Dubner, Levitin’s book demands a reasonable level of reader interest in the subject. (Frankly, the author is better at breezing through Music Theory 101 or Brain Chemistry for Dummies than at keeping a personal anecdote on the leash.)

Although Levitin’s narrative grasp may be shaky, the arc of his transformation from musician to scientist grounds his thinking and guides his treatise to a satisfying conclusion. Drawing on his recording-studio experience, he displays a winning sense of humor about himself and the pop music business. He presents a mathematical basis for why clarinets sound a little odd, declares that “all accordions sound alike” and affectionately corrects the Ramones’ use of the word “cerebellum” in “Teenage Lobotomy.” The musical examples he cites are superbly illustrative and readily accessible.

At its best, “This Is Your Brain on Music” provides a wealth of what psychologists call declarative knowledge, the ability to describe what we know, in this case something we’ve all known since childhood -- precisely what it is we like about music. Parents of a certain age will nod sagely, involuntarily humming the “SpongeBob SquarePants” theme as they read that by age 5 children “have learned to recognize chord progressions in the music of their culture.” By 10 or 11, many “take on music as a real interest, even those children who didn’t express such an interest in music earlier,” Levitin writes. And it’s no coincidence that most people have formed their musical taste by 18 or 20, at the end of adolescence, “the formative phase when our neural circuits become structured out of our experiences.” That’s why as adults, “the music we tend to be nostalgic for, the music that feels like it is ‘our’ music, corresponds to [what] we heard during these years.”

Levitin offers a haunting and perhaps comforting aside: One thing people with Alzheimer’s will often remember is their favorite music from age 14.

The human brain can’t play back endless scenes from childhood, but our favorite songs function as cues, keys that unlock more complex memories. By tracking music’s deep ties to memory, Levitin helps quantify some of music’s magic without breaking its spell.