Voice of the Mind's Ear

Put on glasses that distort the world, and your brain quickly adapts so that you can still find objects correctly. Now a pair of scientists reports that the brain can also adapt to distortions in your voice by changing your speech patterns. The finding, reported in today's issue of Science, suggests a new approach to investigating the causes and possible treatment of speech impairments such as stuttering.

The researchers--John Houde, a psychophysicist at the University of California, San Francisco, and Michael Jordan at the Massachusetts Institute of Technology in Cambridge--developed a computer program that prompts people to pronounce simple words while it simultaneously plays their voice into headphones. During the 2-hour experiment, the computer began to distort the playback of the middle vowel sound so that the word the subjects read did not match what they heard themselves saying. The subjects then learned to adjust their speech so that they thought they heard themselves pronouncing the words correctly.

Understanding the role of hearing in speech may suggest possible new treatments for speech impairments, says Houde. Because the auditory feedback makes patients try different sounds, Houde and Jordan's computer program "is certainly something to try," says Nancy Jackson, a speech pathologist at the Cleveland Hearing and Speech Center in Ohio.