Kenneth Noble Stevens (March 24, 1924 – August 19, 2013) was the Clarence J. LeBel Professor of Electrical Engineering and Computer Science, and professor of health sciences and technology at the research laboratory of electronics at the Massachusetts Institute of Technology. Stevens was head of the speech communication group in MIT's research laboratory of electronics (RLE), and was one of the world's leading scientists in acoustic phonetics. He was awarded the National Medal of Science from President Bill Clinton in 1999, and the IEEE James L. Flanagan Speech and Audio Processing Award in 2004. He died in 2013 from complications of Alzheimer's disease.
Education
Early education Ken Stevens was born in Toronto on March 23, 1924. His older brother, Pete, was born in England; Ken was born four years later, shortly after the family emigrated to Canada. His childhood ambition was to become a doctor, because he admired an uncle who was a doctor. He attended high school at a school attached to the department of education at the University of Toronto. Stevens attended college in the school of engineering at the University of Toronto on a full scholarship. He lived at home throughout his undergraduate years. Though Stevens himself could not fight in World War II because of his visual impairment, his brother was away for the entire war; his parents tuned in nightly to the BBC for updates. Stevens majored in engineering physics at the university, covering topics from the design of motorized machines through to basic physics, which was taught by the physics department. During summers he worked in the defense industry, including one summer at a company that was developing radar. He received both his S.B. and S.M. degrees in 1945. Stevens had been a teacher since his undergraduate years, when he lectured sections of home economics that involved some aspect of physics. After receiving his master's degree, he stayed at the University of Toronto as an instructor, teaching courses to young men returning from the war, including his own older brother. He was a fellow of the Ontario Foundation from 1945 to 1946, then worked as an instructor at the University of Toronto until 1948. During his master's research Stevens became interested in control theory, and took courses from the applied mathematics department, where one of his professors recommended that he should apply to MIT for doctoral studies.
Doctoral studies Shortly after Stevens was admitted to MIT, a new professor named Leo Beranek noticed that Stevens had taken acoustics. Beranek contacted Stevens in Toronto, to ask if he would be a teaching assistant for Beranek's new acoustics course, and Stevens agreed. Shortly after that, Beranek contacted Stevens again to offer him a research position on a new speech project, which Stevens also accepted. The Radiation Laboratory at MIT (building 20) was converted, after the war, into the Research Laboratory of Electronics (RLE); among other labs, RLE hosted Beranek's new Acoustics Lab. In November 1949, the office next to Ken's was given to a visiting doctoral student from Sweden named Gunnar Fant, with whom he formed a friendship and collaboration that would last more than half a century. Stevens focused on the study of vowels during his doctoral research; in 1950 he published a short paper arguing that the autocorrelation could be used to discriminate vowels, while his 1952 doctoral thesis reported perceptual results for vowels synthesized using a set of electronic resonators. Fant convinced Stevens that a transmission-line model of the vocal tract was more flexible than a resonator model and the two published this work together in 1953. Ken credits Fant with the association between the Linguistics Department and the Research Laboratory for Electronics at MIT. Roman Jakobson, a phonologist at Harvard, had an office at MIT by 1957, while Morris Halle joined the MIT Linguistics Department and moved to RLE in 1951. Stevens' collaborations with Halle began with acoustics, but grew to focus on the way in which acoustics and articulation organize the sound systems of language. Stevens defended his doctoral thesis in 1952; his doctoral committee included his adviser Leo Beranek, as well as J. C. R. Licklider and Walter A. Rosenblith. After receiving his doctorate, Stevens went to work at Bolt, Beranek and Newman (now BBN Technologies) in Harvard Square. In the early 1950s, Beranek decided to retire from the MIT faculty in order to work full-time at BBN. He knew that Stevens loved to teach, so he encouraged Stevens to apply for a position on the MIT faculty. Stevens did so, and joined the faculty in 1954.
Research, teaching and service
Scientific contributions Stevens is best known for his contributions to the fields of phonology, speech perception, and speech production. Stevens' most well-known book, Acoustic Phonetics, is organized according to the distinctive features of Stevens' phonological system.
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