Brain Reconstructs Fragmented Sounds Enabling Us to Hear in a Noisy Room

by Savitha C Muppala on  November 28, 2009 at 7:07 PM General Health News   - G J E 4
 Brain Reconstructs Fragmented Sounds Enabling Us to Hear in a Noisy Room
Researchers said that the brain is able to reconstruct fragmented sounds which help us understand each other in a noisy room.

The team from Maastricht University in The Netherlands has unravelled the neural mechanisms associated with this auditory continuity illusion, where a physically interrupted sound is heard as continuing through background noise.

"In our day-to-day lives, sounds we wish to pay attention to may be distorted or masked by background noise, which means that some of the information gets lost. In spite of this, our brains manage to fill in the information gaps, giving us an overall 'image' of the sound," said senior study author, Dr. Lars Riecke from the Department of Cognitive Neuroscience at Maastricht University in The Netherlands.

During the study, researchers investigated the timing of sensory-perceptual processes associated with the encoding of physically interrupted sounds and their auditory restoration, respectively, by combining behavioural measures where a participant rated the continuity of a tone, with simultaneous measures of electrical activity in the brain.

They found that slow brain waves called theta oscillations, which are involved in encoding boundaries of sounds, were suppressed during an interruption in a sound when that sound was illusorily restored.

"It was as if a physically uninterrupted sound was encoded in the brain," said Riecke.

This restoration-related suppression was most obvious in the right auditory cortex.

"Our results revealed that spontaneous modulations in slow evoked auditory cortical oscillations may determine the perceived continuity of fragmented sounds in noise," said Riecke.

The suppressive effect was present before an illusorily filled gap and reached maximum shortly after the gap's actual onset, suggesting that the mechanism may work rapidly or anticipatorily and thereby facilitate stable hearing of fragmented sounds in natural environments.

The authors also suggest that their results might inspire future design of devices to assist people with hearing deficits.

The study appears in journal Neuron, published by Cell Press.

Source: ANI

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