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May 2007 Issue

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Speech Offers Clues to Sleepiness

Published May 2007

Finding ways to measure “sleepiness” has become increasingly important to a number of professions, including the military, the transportation industry, home health care and even forensic experts.

Poor memory, short attention span and impaired motor coordination are often the most noticeable effects of sleep deprivation, but changes in speech clarity—although not obvious to the average listener—may also be a sign of serious lack of sleep.

UC speech researcher Suzanne Boyce, PhD, hopes that by identifying speech changes in sleep-deprived individuals, new, noninvasive steps can be taken to help the number of fields interested in this topic.

The National Heart, Lung, and Blood Institute of the National Institutes of Health (NIH) has awarded Boyce a $467,000, two-year grant to demonstrate speech changes in the sleep deprived. She’ll study speech recordings taken through a partnership between NIH’s National Institute on Deafness and Other Communication Disorders and Walter Reed Army Institute of Research.

Boyce, associate professor in the communication sciences and disorders department in UC’s College of Allied Health Sciences, will use speech recognition technology to listen for abrupt changes in the speech spectrum.

“People who are sleep deprived probably don’t try quite as hard to pronounce each sound, and/or take as big a breath as they need before speaking,” says Boyce. “The result will be that speakers fail to put as much emphasis on consonant sounds as their more ‘awake’ counterparts. And vowels are sometimes slurred.”

Recognizing many of these changes, however, can be extremely difficult for the typical listener, says Boyce.

“Speech may be the most robust function in sleep-deprived individuals,” Boyce adds. “It’s not so obviously impaired until a person is extremely deprived of sleep. But beyond that, listeners are very good at understanding what someone is trying to say, so noticing speech changes is rare.”

Because studying speech patterns can be as noninvasive as making a simple recording, Boyce says, the sounds we make—or don’t make—may prove invaluable to the number of professions that rely on their workers being wide awake and alert at all times.

And finding noninvasive tools for measuring sleepiness, Boyce says, could also help home health care workers when testing patients for sleep apnea, and even forensic analysts trying to determine causes of accidents.

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