Anyone who has tried to carry on a conversation in a roomful of talkers knows how difficult it can be to concentrate on what one person is saying while tuning everyone else out.
Researchers at the University of Maryland, Johns Hopkins University, and Starkey Laboratories, Inc. have a better picture of how the brain manages this feat. Using magnetoencephalography (MEG), an imaging technique that measures magnetic fields produced by changes in the brain's electrical activity, the researchers played two competing audio streams into the ears of 26 healthy volunteers and asked them to listen to one stream while ignoring the other.
One group concentrated on a faster-paced series of beeps while the second group focused on a slower beep pattern; the groups later switched tasks to focus on the other audio stream. The researchers also introduced an occasional change in the rhythm to find out if the study volunteers noticed.
Among their results, researchers found that people listening to one stream did not detect pattern changes in the other stream. In addition, although the brain showed neural activity representing both audio streams, the amount of neural activity was much stronger and more in sync for the stream on which a person was concentrating.
Supported by the National Institute on Deafness and Other Communication Disorders, one of the National Institutes of Health, the scientists are presenting their findings at the 2009 Midwinter Meeting of the Association for Research in Otolaryngology in Baltimore.
Materials provided by NIH/National Institute on Deafness and Other Communication Disorders. Note: Content may be edited for style and length.
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