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Journal recognizes local audiology study

What qualities make a professional research paper good? Ask Susan Dalebout, academic assistant professor of communication disorders, or doctoral student Lisa Fox.

The two are co-authors of a study recently awarded the editor's prize for the best article of 2000 by the Journal of the American Academy of Audiology.

The two audiologyresearchers from the Curry School of Education studied electrical signals generated by the brain in response to different sound stimuli.

The goal of their research is to use neuroelectrical signals "as a tool for learning about speech perception, both normal and abnormal, primarily in kids," Dalebout said.

Now audiologists use behavioral tests to diagnose school-aged children who have difficulty hearing or processing spoken language with Central Auditory Processing Disorder.

But, doctors have trouble distinguishing this disorder from other problems, such as attention deficit disorder or learning disabilities, because many symptoms are similar.

In an effort to make diagnoses more objective, scientists like Dalebout and Fox are searching for physical measures, such as electrical impulses from the brain, that can be used to diagnose children with CAPD.

Specifically, the researchers studied a type of evoked response called mismatch negativity. "Evoked responses are patterns of [brain] activity in response to stimuli," Dalebout said.

Mismatch negativity is a specific type of evoked response generated when a person hears a mismatch.

 
Related Links
  • America Academy of Audiology web site
  • Dalebout explained how this occurs: For example, imagine someone sitting in a chair with electrodes taped to your face, listening to a voice repeating a stream of syllables "da, da, da." The person no longer registers the syllables, but the brain processes the sounds and builds a neural template for the sound "da."

    For each additional syllable, the brain compares the current sound to the old "da" template to see if they match.

    As long as the voice keeps repeating the syllable "da," the brain identifies the match and gives off a specific pattern of neuroelectric impulses indicating a match.

    But, if the voice suddenly replaces one of the syllables in the stream with another syllable, the brain releases a different pattern of electrical impulses to indicate a mismatch.

    In theory, researchers can identify when a listener hears a sound mismatch by analyzing brain activity patterns. Mismatch negativity may help researchers identify CAPD.

    Children who process sounds properly would exhibit mismatch negativity, while those with a disorder would not register the difference between mismatched syllables, Dalebout said.

    In past studies, researchers performed a stream of syllables experiment on thousands of listeners, she said.

    They averaged all brain activity patterns when the syllables were matched and mismatched. They found that the average pattern of the matched brain waves was different from the mismatched brain waves, as expected.

    This research indicated it was possible to determine mismatch negativity in populations.

    Dalebout and Fox's award-winning research focused on how effectively they were able to identify mismatch negavitity.

    Instead of averaging over many listeners, they analyzed the same listener many times.

    Surprisingly, they found that it was very difficult to determine mismatch negativity in individuals. This result was different from most other published work on mismatch negativity.

    "With this paper we put ourselves out on a line - it was kind of against the norm," Fox said. "We certainly put a lot of effort into it. It's rewarding to get such recognition but also to have people validate our work."

    Fox is continuing to work on mismatch negativity, trying to improve analysis methods so the technique can be used effectively in individuals.

    Dalebout now is researching other types of evoked responses to determine if they are more tractable than mismatched negativity.

    The editorial board of the Journal of the American Academy of Audiology selected Dalebout and Fox's work "because it directly addressed contemporary clinical issues of importance through exceptionally sound scholarship, most rigorous and carefully conducted science, and impeccable writing."

    Interestingly, the board decided the best research paper was one with a negative result researchers did not expect.

    "The award showed that even though [our research] wasn't a positive finding, it didn't mean it wasn't important," Fox said.

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