Bell Labs Speech Coding Pioneer Bishnu Atal Dies at 93

Bishnu Saroop Atal, the Bell Labs researcher whose speech-coding techniques still carry voice traffic on cellular networks worldwide, died on 19 August at 93. His work on linear predictive coding and code-excited linear prediction remains the backbone of low-bit-rate voice transmission more than six decades after he joined Murray Hill, N.J., in 1961.

Atal received the 2013 IEEE Jack S. Kilby Signal Processing Medal for what the citation called "fundamental and pioneering contributions to speech coding." The citation matters here. It confirms what the industry has long treated as settled fact: the algorithms Atal built at Bell Labs, and later at AT&T's Shannon Laboratory in Florham Park, N.J., became the foundation for efficient, high-quality voice transmission over digital cellular systems.

What did Atal actually build?

Three techniques define his career.

• Linear predictive coding (LPC). During the 1960s, Atal helped develop this method for analyzing and compressing speech. LPC is now the most widely used method for encoding speech at a low bit rate.
• Multipulse LPC. Atal refined the core technique to improve the quality of compressed speech.
• Code-excited linear prediction (CELP). Developed with colleague Manfred R. Schroeder, CELP produces high-quality speech at very low bit rates.

CELP deserves the commercial emphasis. It let digital communications systems carry voice using less bandwidth, and that efficiency translated directly into cellular capacity. Wireless networks could handle more simultaneous calls on the same spectrum. Every subscriber who made a call on a congested network without a dropped connection owed something to this work, though no carrier ever billed it that way.

What came after the lab work?

Atal led the acoustics and speech research departments at Bell Labs. The company named him a Fellow in 1994. When AT&T Bell Laboratories split into separate research organizations in 1996, Atal moved to AT&T's Florham Park headquarters, and AT&T named him a Fellow the following year. He retired in 2002.

Retirement did not end the research. He became an affiliate professor of electrical engineering at the University of Washington in Seattle, where he continued work on speech processing, speech recognition, and high-dimensional computing.

His credentials accumulated steadily. He was elected to the National Academy of Engineering in 1987 and the National Academy of Sciences in 1993. He received the 2018 International Speech Communication Association Medal for Scientific Achievement and a 2003 medal from the Franklin Institute.

His education spanned two continents. He earned a bachelor's degree in physics in 1952 from the University of Lucknow in India, and a master's degree in electrical engineering in 1955 from the Indian Institute of Science in Bengaluru. He completed a Ph.D. in electrical engineering in 1968 at the Polytechnic Institute of Brooklyn, now NYU's Tandon engineering school, while working full time at Bell Labs.

Which other engineers did the community lose?

The same period took four other IEEE members whose careers touched semiconductors, space systems, and industrial electronics.

Darryl Palmer Jr., senior member and chair of the IEEE Central Illinois Section, died on 30 August at 55. In 1986, at age 16, he completed a summer internship at NASA's Glenn Research Center in Cleveland and helped develop FoilSim, an educational aerodynamics program. He later designed hardware and software systems for thermal wave imaging at Glenn, software for General Motors' North American robotic and welding division, and EngineSim, which models jet engine design. NASA awarded him a Space Act Award. After earning his computer science degree in 2000, he worked at Danfoss Drives in Loves Park, Ill., on embedded control systems for variable-frequency drives and sensorless control for oil-field beam pumps. He and his wife Alexandra "Sasha" Goodwin founded Janus Choice, a health technology platform, in 2014; he served as CEO until the company closed in 2020. He finished his career as a control systems team lead at Caterpillar in Peoria, Ill.

Henry Leopold Richter, life senior member, died on 12 August at 99. A Caltech Ph.D. from 1956, he joined NASA's Jet Propulsion Laboratory in 1955 and rose to section chief, responsible for scientific instruments on the Ranger, Surveyor, and Mariner programs. He helped develop NASA's Deep Space Network. When Explorer 1 launched in January 1958, Richter coordinated tracking stations with the San Gabriel Valley Radio Club. He later became vice president and technical director of Xerox Electro-Optical Systems, then a communications engineer for the Los Angeles County Sheriff's Department, and ran a public safety telecommunications consultancy for more than 20 years. The Radio Club of America gave him its Lifetime Achievement Award in 2019.

Raymond L. Giordano, life member and former RCA engineer, died on 19 July at 91. He designed integrated circuits and defense electronics at RCA, Harris, and Intersil, and designed circuitry for Kodak's Cameo cameras and a laser printer. His patents include a smoke detector chip for Siemens, a speed control chip for Ford, an engine control system for Delco Remy, and a control component for Chrysler.

Delano D. Wilson, life Fellow and president of Power Technologies in Schenectady, N.Y., died on 26 May at 92. A former GE R&D director, he joined the electric power consulting firm in 1974, authored six books and 65 technical papers, and held two patents.

Daniel I. Amey Jr., life Fellow and electronic packaging engineer, died on 12 March at 84. His career ran from General Dynamics in 1963 through Sperry Univac, Thomas & Betts, Elco, and DuPont, where he retired as a research fellow. His packaging work covered large-scale integration packages, hybrid circuits, connectors, and printed wiring board processes. He wrote more than 70 technical papers, held more than 14 patents, and received IMAPS's 2004 Wagnon Technical Achievement Award.

Atal's death removes the last living link to the era when Bell Labs defined speech coding as a discipline, but the techniques he created remain embedded in every low-bit-rate voice standard deployed today, and no successor method has displaced them.