Later Years
Among the work that he is best known for are Fletcher's contributions to the theory of speech perception. He showed that speech features are usually spread over a wide frequency range, and developed the articulation index to approximately quantify the quality of a speech channel. He also developed the concepts of, equal-loudness contours, loudness scaling and summation, and the critical band. As Director of Research at Bell Labs, he oversaw research in electrical sound recording, including more than 100 stereo recordings with conductor Leopold Stokowski in 1931-2.
Much of his research is considered to be authoritative, and his books, Speech and Hearing and Speech and Hearing in Communication, are landmark treatises on the subject.
Read more about this topic: Harvey Fletcher
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