An electrical engineer, in World War II Flanagan joined the U.S. Army Air Forces, and worked on scrambling communications and on radar. After going back for his college degree, in 1957 Flanagan was hired as an acoustical researcher for AT&T’s Bell Laboratories, where he worked on improving the audio quality of phone systems — which had far-reaching applications. By 1961 he was the head of the Lab’s Speech and Auditory Research Department, then promoted in 1967 to head the Acoustics Research Department. In 1976, he presented his research ideas in the Proceedings of the I.E.E.E. — “Computers That Talk and Listen: Man-Machine Communication by Voice” — laying the groundwork for how humans and computers could communicate by speech.
“What is so significant about this article is that it painted a picture of society in the 21st century in a paper published 39 years ago,” says Lawrence R. Rabiner, a former colleague who now teaches at both Rutgers and the University of California at Santa Barbara. “How much more vision could anyone have at that time?” That groundwork led to smartphone “digital assistants” like Apple’s “Siri”, and automated voice processing when you call a company’s customer service line, for more recent examples. Flanagan developed encoders that would listen to human speech, adapt to the speaker’s manner of speech, and digitize it so that computers could determine what the person was saying. On the other side, he developed speech synthesis methodologies to go in the other direction, so that computers could speak to humans in voices that could be understood. That, in turn, led to improvements in signal processing so that voice announcements would be intelligible in much more challenging situations, such as football stadiums and subway platforms. Along the way, Flanagan’s research led directly to voicemail systems, the artificial human larynx, and digital sound storage — which led to the MP3 audio standard, which led to digital music players. Flanagan retired from Bell Labs in 1990, and went on to teach at Rutgers University, where he was director of the Center for Advanced Information Processing. He was awarded at least 50 patents, the National Medal of Science, and the L.M. Ericsson International Prize in Telecommunications. Dr. Flanagan mostly retired in 2005, and died from congestive heart failure at his New Jersey home on August 25, the day before he turned 90.