By: Clive Thompson

Music of the Hemispheres   (page 2)

For his first experiment he came up with an elegant concept: He stopped people on the street and asked them to sing, entirely from memory, one of their favorite hit songs. The results were astonishingly accurate.

Most people could hit the tempo of the original song within a four-percent margin of error, and two-thirds sang within a semitone of the original pitch, a level of accuracy that wouldn’t embarrass a pro.

“When you played the recording of them singing alongside the actual recording of the original song, it sounded like they were singing along,” Dr. Levitin said.

It was a remarkable feat. Most memories degrade and distort with time; why would pop music memories be so sharply encoded? Perhaps because music triggers the reward centers in our brains. In a study published last year Dr. Levitin and group of neuroscientists mapped out precisely how.

Observing 13 subjects who listened to classical music while in an M.R.I. machine, the scientists found a cascade of brain-chemical activity. First the music triggered the forebrain, as it analyzed the structure and meaning of the tune. Then the nucleus accumbus and ventral tegmental area activated to release dopamine, a chemical that triggers the brain’s sense of reward.

The cerebellum, an area normally associated with physical movement, reacted too, responding to what Dr. Levitin suspected was the brain’s predictions of where the song was going to go. As the brain internalizes the tempo, rhythm and emotional peaks of a song, the cerebellum begins reacting every time the song produces tension (that is, subtle deviations from its normal melody or tempo).

“When we saw all this activity going on precisely in sync, in this order, we knew we had the smoking gun,” he said. “We’ve always known that music is good for improving your mood. But this showed precisely how it happens.”

The subtlest reason that pop music is so flavorful to our brains is that it relies so strongly on timbre. Timbre is a peculiar blend of tones in any sound; it is why a tuba sounds so different from a flute even when they are playing the same melody in the same key.

Popular performers or groups, Dr. Levitin argued, are pleasing not because of any particular virtuosity, but because they create an overall timbre that remains consistent from song to song. That quality explains why, for example, I could identify even a single note of Elton John’s “Benny and the Jets.”

“Nobody else’s piano sounds quite like that,” he said, referring to Mr. John. “Pop musicians compose with timbre. Pitch and harmony are becoming less important.”

Dr. Levitin dragged me over to a lab computer to show me what he was talking about. “Listen to this,” he said, and played an MP3. It was pretty awful: a poorly recorded, nasal-sounding British band performing, for some reason, a Spanish-themed ballad.

Dr. Levitin grinned. “That,” he said, “is the original demo tape of the Beatles. It was rejected by every record company. And you can see why. To you and me it sounds terrible. But  George Martin heard this and thought, ‘Oh yeah, I can imagine a multibillion-dollar industry built on this.’

“Now that’s musical genius.”

THE largest audience that Dr. Levitin has performed in front of was 1,000 people, when he played backup saxophone for Mel Tormé. Years of being onstage piqued Dr. Levitin’s interest in another aspect of musical experience: watching bands perform. Does the brain experience a live performance differently from a recorded one?

To find out, he and Bradley Vines, a graduate student, devised an interesting experiment. They took two clarinet performances and played them for three groups of listeners: one that heard audio only; one that saw a video only; and one that had audio and video. As each group listened, participants used a slider to indicate how their level of tension was rising or falling.

One rapid, complex passage caused tension in all groups, but less in the one watching and listening simultaneously. Why? Possibly, Dr. Levitin said, because of the performer’s body language: the clarinetist appeared to be relaxed even during that rapid-fire passage, and the audience picked up on his visual cues. The reverse was also true: when the clarinetist played in a subdued way but appeared animated, the people with only video felt more tension than those with only audio.