"You're at a party. Music is playing. Glasses are clinking. Dozens of conversations are driving up the decibel level. Yet amid all those distractions, you can zero in on the one conversation you want to hear.
This ability to hyper-focus on one stream of sound amid a cacophony of others is what researchers call the "cocktail-party effect." Now, scientists at the University of California in San Francisco have pinpointed where that sound-editing process occurs in the brain—in the auditory cortex just behind the ear, not in areas of higher thought. The auditory cortex boosts some sounds and turns down others so that when the signal reaches the higher brain, "it's as if only one person was speaking alone," says principle investigator Edward Chang.
These findings, published in the journal Nature last week, underscore why people aren't very good at multitasking—our brains are wired for "selective attention" and can focus on only one thing at a time. That innate ability has helped humans survive in a world buzzing with visual and auditory stimulation. But we keep trying to push the limits with multitasking, sometimes with tragic consequences. Drivers talking on cellphones, for example, are four times as likely to get into traffic accidents as those who aren't."