Tiny cell phone chip aims to improve sound quality

The company, Audience, will demonstrate the circuit on Monday on the first day of the Mobile World Congress, a cellular industry trade show in Barcelona. The circuit, the company's first product, is a chip that is only slightly larger than a grain of sand. The company said the device would offer higher quality noise suppression than the software that performs this function in today's cell phones.

Speech quality is of increasing importance in the cell phone industry, Peter Santos, the chief executive, said. "Voice quality is one of the top three reasons for customer churn."

Noise suppression can also play an important role in making cell phone networks more efficient, he said. When phones transmit extraneous noise beyond the speakers' voices, precious network bandwidth is wasted, he said.

The technology can also help improve the quality of the speakerphone function of a cell phone. Using a cell phone as a speakerphone requires improved performance from the circuitry in a phone that identifies a speaker's voice.

The company demonstrates its system by placing a cell phone call from a room where loud rock music is being played. When the noise suppression chip is turned on, there is a striking decline in background noise while the speaker's voice remains clearly audible.

Santos said the company's technology has already been adopted by several major handset manufacturers, and they will announce its inclusion in their products this year.

Audience was founded in 2000 by Lloyd Watts, a neuroscientist who studied with the physicist Carver Mead of the California Institute of Technology. Before founding Audience, which is based in Mountain View, Calif., Watts was a member of a group of technologists at Interval Research, a Silicon Valley research company backed by Paul Allen, a co-founder of Microsoft. Allen, along with several venture capital firms, is also financing Audience.

The Audience chip sits between the microphone and the cell phone circuitry. It runs software the company has developed that takes digitized sound and represents it as a three-dimensional matrix. That representation makes it possible for the circuitry to identify and then suppress noise picked up by the cell phone microphone while leaving the speaker's voice intact.

The company says the system has the ability to identify and block up to 25 decibels of extraneous sound.

The Audience technology can be traced to work Watts began as a graduate student working in a laboratory at Cal Tech. There he designed a chip that modeled the human cochlea, the snail-like organ in the inner ear that converts vibrations into electrical signals that are perceived by the brain as sound.