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Sergei Kochkin, PhD, is Director of Market Development and Market Research for Knowles Electronics, Inc. He also serves as chairman of the Market Development Committee of the Hearing Industries Association and is a board member of the Better Hearing Institute. Correspondence to Dr. Kochkin at Knowles Electronics, 1151 Maplewood Drive, Itasca, IL 60143.
Sergei Kochkin (Tue,) studied this question.