Bishnu Saroop Atal
Acoustics and signal processing pioneer
Life Fellow, 93; died 19 August

Atal was an acoustics and signal processing researcher at Bell Labs in Murray Hill, N.J., and later at AT&T’s Shannon Laboratory, in Florham Park, N.J. His pioneering work on voice-coding techniques became the foundation for efficient, high-quality voice transmission over cellular networks. He received the 2013 IEEE Jack S. Kilby Signal Processing Medal for “fundamental and pioneering contributions to speech coding.”

He joined Bell Labs in 1961 as a communications researcher, and his early work there focused on speaker identification technology. During the 1960s he helped develop linear predictive coding, a powerful method for analyzing and compressing speech. LPC is now the most widely used method for encoding speech at a low bit rate.

Atal developed increasingly sophisticated low-bit-rate speech-coding techniques. They included multipulse LPC, which improved the quality of compressed speech.

He also worked with his colleague Manfred R. Schroeder to develop code-excited linear prediction, a method for producing high-quality speech at very low bit rates. CELP became a foundational technique in modern speech coding, letting digital communications systems carry voice using less bandwidth. The extra efficiency expanded cellular capacity, allowing wireless networks to handle more simultaneous calls.

Later in his career, he led the acoustics and speech research departments at Bell.

The company named him a Fellow in 1994. When AT&T Bell Laboratories split into separate research organizations in 1996, Atal continued his career at the AT&T Florham Park headquarters, and he was named a Fellow the following year.

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