Archive for Tuesday, December 30, 2008

Hard to hear at holiday parties? Blame your brain

December 30, 2008


— It’s almost New Year’s Eve, a time for plunging into boisterous crowds bathed in loud music. And for some of us, that means turning to an old friend and hearing things like this:

“Did you know (BOOM-da-da-BOOM) went over (Bob! You look wonder-) so she said (clink-clink) and then I (Here, have another one) what would you do?”

Huh? Too noisy to hear! But wait — how come these younger people understood what she said? What’s wrong with your ears?

Actually, part of the problem may be your brain.

In fact, it may lie in your brain’s dimmer switch for controlling the input from your ears. That bit of brain circuitry appears to falter with age, and scientists are getting some clues about why.

If you have trouble understanding conversation in a noisy room, you’re experiencing what’s sometimes called the cocktail party problem.

That can be one of the first signs of an age-related hearing loss — a more general problem that can creep in during middle age, and affects one-third of adults ages 65 to 75.

Scientists are still trying to piece together why our hearing goes downhill with age, with the goal of trying to slow it or even reverse it.

When it comes to the cocktail party problem, the dimmer switch is a piece of that story, though it’s not clear just how big a factor.

“I think it’s a significant player,” said Robert Frisina of the University of Rochester in New York, who is studying it.

Scientists have long known that the brain not only receives signals from the ears but can also talk back to them. And when there’s too much noise, this dimmer-switch brain circuitry tells the ears to reduce their flow of signals to the brain.

This helps the sensitive auditory system handle loud sounds that otherwise would overwhelm it and become distorted, as when a radio is turned up too loud for the speaker to handle. In addition, since background noise at a party tends to be lower-pitched than speech sounds, the dimmer switch probably can block out that distracting noise more than it does the speech, Frisina said.

The brain has an added trick for focusing on a particular person’s speech rather than competing conversations, Frisina said. Since you’re probably facing the person you want to hear, his words arrive at both your ears at the same time and at the same volume. The brain can use that, along with the dimmer switch, to home in on that person’s speech, Frisina said.


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