CHAMPAIGN, Ill. -- For people with hypernasal speech, many of them with repaired cleft palates, there have been few remedies other than surgery, and the surgery comes with risks.
Some of these people, however, may find help in a kind of weight-lifting for the soft palate, says David Kuehn, a professor of speech and hearing science at the University of Illinois.
Making use of a device for treating sleep apnea, Kuehn devised a treatment almost a decade ago to strengthen the muscles of the soft palate, which acts as the door between the oral and nasal cavities. To produce most language sounds, the door should be closed, but people with hypernasal speech are unable to close it completely. Stronger muscles, Kuehn reasoned, might make it possible for subjects to close that door more tightly, reducing their nasality and getting closer to normal-sounding speech.
With results from a study completed last year, Kuehn now has evidence his therapy works. "For the first time, we have hard data to back up a statement that this therapy does, in fact, statistically reduce hypernasality in a fairly large group of subjects," he said.
He'll present those results at conferences this month in Nashville and Atlanta.
The therapy is known as CPAP, which stands for "continuous positive airway pressure." A face mask is firmly sealed around a patient's nostrils and the CPAP machine maintains a set pressure within the nasal cavity, preventing the soft palate from closing the velopharynx, or oral-nasal passageway. For people with sleep apnea, it's that closing that can stop their breathing and force them to wake up.
In Kuehn's treatment for hypernasality, the device works the same way, keeping the passageway open. But instead of wearing it during sleep, patients in the study wear it during a daily routine in which they pronounce letters and words in a defined order. The routine forces them to work the muscles of the soft palate against the resistance of the air pressure keeping the passageway open.
"Much like lifting weights to strengthen the biceps of the arms, this procedure is designed to strengthen the muscles that elevate the soft palate and the muscles that draw the pharyngeal walls [the walls of the pharynx] inward," Kuehn said. Over the eight weeks, the daily session time was increased from 10 to 24 minutes, and the air pressure gradually was increased as well.
A total of 43 subjects were evaluated in the study, a large sample for research of this kind, Kuehn noted. All but one of the subjects was under the age of 19, with 24 of them male and 19 female. To attract the needed numbers, the study was conducted in clinical centers on eight Midwestern campuses.
The evidence that the subjects improved was drawn from a blind analysis by six trained investigators who listened to random speech samples recorded before, during and after the eight weeks of the therapy. Additional evidence came from readings of those samples by calibrated nasometers, electronic devices designed to measure degrees of nasality.
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