Speech Communication Group

Speech Communication Group at MIT

Speech Research

illustration of speech Coming Soon

Gesture Research

illustration of gesture Gesture Research

We are a research group of speech and gesture scientists under MIT's Research Laboratory of Electronics (rle.mit.edu).

In Memory of Ken Stevens

On the day Kenneth Noble Stevens was first appointed at MIT as an Assistant Professor in 1954, no one could have predicted the number of scientific careers he would launch, the way he would transform the thinking of his students and colleagues, and the breadth of the influence he would have on acoustic phonetics and beyond. He was a member of the MIT faculty for more than half a century and supervised at least 50 Ph.D. dissertations, as well as an untold number of Masters students, undergraduates, postdoctoral fellows, and visiting scientists. His first Ph.D. student was James Flanagan (1955), and his last one was Youngsook Jung (2009).

Ken Stevens
Ken Stevens (Photo Credit: Greg Hren, MIT RLE)

Being in Ken’s Speech Communication Laboratory was an extraordinary experience. The laboratory was full of energy and brought together researchers from many disciplines related to speech (linguistics, psychology, acoustics, computer science, physiology). This was at a time when multidisciplinary research was not the norm in either academia or industry. Ken was also unique, for his time, in that he supervised a substantial number of female graduate students. In fact, of the first 20 women who received PhD’s in Electrical Engineering and Computer Science at MIT, four were Ken’s students, and of the doctoral students he supervised, 23 were women.

Ken was a gentle and rigorous mentor, and met regularly with his students and postdocs. As Haruko Kawasaki, a former postdoc with Ken, says, “What struck me most about Ken at these meetings was his being an exceptionally good listener.” He had a low-key manner, yet he would let his students know when something was not right, sometimes by simply raising one eyebrow! Patti Price, another former postdoc of Ken, recalls him telling her, “Well, when you measure productivity and a student is involved, you have to count both products: the progress of the research and the progress of the student.” His legendary support of students is reflected in his reluctance to put his name on their papers, even though he would spend uncounted hours discussing the work and editing successive drafts.

The depth of his understanding of science formed an indelible imprint on his students and colleagues that became a model for those who pursued scientific careers, so that Ken's influence reached far beyond any particular time and place. He was creative yet meticulous in his attention to understanding and explaining every detail of a model or of a physical mechanism. He also used words with great precision. It is no surprise, then, that his 1998 *Acoustic Phonetics* book, which became a classic overnight, took more than 20 years to complete. Among his seminal intellectual contributions is the quantal theory of speech production relating the underlying sound categories of language to the acoustics, physiology, and physics of the vocal tract. Another is his 2002 model of speech perception based on feature cues such as landmarks. His long-term collaborations with colleagues such as Gunnar Fant, Morris Halle, Sheila Blumstein, Dennis Klatt, and Jay Keyser led to important papers and lively debates on issues such as Analysis-by-Synthesis, Invariance, Distinctive Features, Lexical Access, and Feature Enhancement. He also treasured his friendship and collaboration with Amar Bose, which led to a co-authored book on introductory network theory in 1965. In addition to developing theories of speech production and perception, Ken also helped develop several systems, including the Klatttalk (with Dennis Klatt) and HLSYN speech synthesizers, articulatory synthesis, automatic speech recognition (especially using acoustic landmarks), and speech training methods for deaf children.

Ken Stevens teaching

Ken supported the Acoustical Society of America (ASA) and believed it was the appropriate venue for promoting, discussing, and publishing all things related to speech acoustics. He served as a member of the ASA executive council, and as the Vice President and then President of the organization. In recognition of his scientific contributions and influence, the ASA awarded Ken its Silver Medal in 1983 and its Gold Medal in 1995.  In 1999, President Clinton awarded Ken the National Medal of Science “For his leadership and pioneering contributions to the theory of acoustics of speech production and perception, development of mathematical methods of analysis and modeling to study the acoustics of speech production, and establishing the contemporary foundations of speech science."

Ken was devoted to his family and six children. He was an avid fan of the outdoors and took great pleasure in biking, hiking, skiing, and working on his house in Maine with family and friends. He loved classical music, ice cream, and fish chowder, and was a well-tested cook of lasagna and chili.

Kenneth N. Stevens was born on March 24, 1924, in Toronto, Canada.  He received his B.A.Sc. and M.A.Sc. in engineering physics from the University of Toronto in 1945 and 1948 respectively, and his Sc.D. in electrical engineering from MIT in 1952. His dissertation was entitled “Perception of Sounds Shaped by Resonance Circuits”. His advisor was Leo Beranek; other thesis committee advisors included J.C. Licklider and Walter Rosenblith. Ken died in Clackamas, Oregon on August 19th, 2013 of complications due to Alzheimer’s.  For those of us who knew him, he will always be present in our thoughts, our work, our lives, and our teaching to our own students.

  • Abeer Alwan, UCLA, Los Angeles, CA
  • Stefanie Shattuck-Hufnagel, RLE, MIT, Cambridge, MA
  • Maria-Gabriella DiBenedetto, Sapienza University of Rome, Italy