While in this research it was the pause that proved significant, Menon said any significant change in the composition, such as tempo, an unexpected chord or a sudden change in pitch, would have had a similar effect. It would serve as a marker, allowing the brain to record that section and anticipate the next, since it obviously isn't possible for the listener to remember the entire symphony as a single unit. Scientists call it "event segmentations."
Eighteen persons (10 men and eight women) who had no formal training in music took part in the study. Boyce's compositions were used for the experiment because they comprise well-defined movements, so a brief pause would signal a change in the piece even for people with little musical experience. The participants listened to the music through earphones while they were inside the noisy scanner, and all of them showed some effect from the pauses.
"The signal during these pauses was very, very strong," Menon said. Analysis of 10 seconds surrounding the pause showed activity in two brain regions, the ventral region of the prefrontal cortex, which triggered activity in the second area, the dorsal region. That is considered significant because the active regions were in the right hemisphere of the brain, which is believed to be involved in processing music.
The differences in activity between the right and left sides of the brain were described as "striking" by the research team, which includes several musicians, Devarajan Sridharan, Chris H. Chafe and Jonathan Berger of Stanford, and Daniel J. Levitin of McGill University in Montreal.
Perhaps surprisingly, there was a physical, not just a mental, response among the participants.
"It wasn't just a brain signal," Menon said. "There was also a physiological signal. The heart rate became more variable (during the pause). So there's something interesting happening."
The finding has applications far beyond the field of music, he added. It helps explain, for example, how we can somehow listen to one conversation in a crowded room of gabbers. Slight changes in the other person's voice allow a listener to break down the conversation into understandable "chunks," as Menon put it, and focus attention on that one person.
It's also why the pregnant pause is so useful to comedians and composers, as well as the person you're trying to listen to in a noisy room.
Lee Dye is a former science writer for the Los Angeles Times. He now lives in Juneau, Alaska.