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Professors collaborate on speech coding textbook

TO and Sim
Professors Madihally Narsimha and Tokunbo Ogunfunmi; Photo credit: Heidi Williams

Spend a few minutes talking with associate professor of electrical engineering Tokunbo Ogunfunmi and adjunct lecturer Madihally (Sim) Narasimha (who is also Senior Director of Technology at Qualcomm, Inc. and Consulting Professor of Electrical Engineering at Stanford University) and you learn two things right off the bat—these two are passionate about speech coding and they talk really FAST! Maybe that is why they focus their research on improving methods of transmitting speech via today’s technologies such as VoIP and cellular phones. Recently, they collaborated on writing a textbook, Principles of Speech Coding (available on, for their graduate level courses Speech Coding I, II (ELEN 421, 422), and Voice-over-IP (ELEN 432).

The two met at Stanford University. “I asked him to come to SCU and teach,” said Ogunfunmi. “We had both been teaching speech coding for years, but there was no textbook available. It had been on my mind for some time to write a book, so when Sim came to Santa Clara, it was a good time to move forward.”

The book covers the different standards and philosophies of speech coding for various communication devices. “The appropriate coding algorithm for each telephone conversation must be negotiated at call setup time as sound quality differs with the available bandwidth,” said Narashima; “and students need to understand the nuances of all these algorithms.”

Both agree that this field continues to evolve and grow as newer technologies are constantly emerging. “Skype is a good example of how technology is driving this research,” said Ogunfunmi. “Skype allows users to talk over the Internet, but the Internet channel is not reliable, it is not amenable to real-time communication as it uses packet switching to send information and the components do not necessarily arrive in the proper order, or at all. But the Internet is quickly becoming the ubiquitous network,” he continued, “and our challenge is teach students to adapt other communication tools to the web, to improve the quality of speech transmission in different communication environments.”

“Speech Coding is a technology that is taken for granted, but this business is not going to disappear,” adds Narasimha, “Speech is the fundamental basis of communication for humans; it will always be important.”