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Algorithm tunes voice quality on mobile phones

Posted: 04 Apr 2002 ?? ?Print Version ?Bookmark and Share

Keywords:data communications? wireless? mobile phone? algorithm? DSP?

Though data communications may be the future of wireless transport, voice is the big revenue generator at present. To improve the quality of voice transmissions, Sound ID has developed an algorithm that adjusts and enhances sound quality in mobile phones.

Founded by Stanford University otologist Rodney Perkins, Sound ID has developed a digital signal processing (DSP) algorithm that adapts to changes in background noise to amplify voice signals on a mobile phone. The technology was designed with an understanding of the inner ear in mind, said Scott Rader, executive vice president of marketing and business development at Sound ID.

Changes in background noise are detected through a microphone and characterized by frequency and loudness, Rader said. Once a change is detected, the compression software takes a measure of the background noise, looks for voice sounds in the noise floor and then amplifies them so that a user can better hear the person speaking at the other end.

The algorithm can adjust to changes in background noise within a millisecond, Rader said. The compression technology can work across a set of audio bands, and operates across six to 12 in the case of mobile phones, Rader said.

The algorithm must tackle more than background noise, however, because some users are challenged to simply hear a conversation on a mobile phone, Rader said. "We all hear differently," he said, "[so] we optimize sound for how people hear."

Users of mobile phones housing Sound ID's algorithm technology can adjust the sound quality of a phone to meet their needs. Then, using a software suite provided by Sound ID, network operators can store user-specific sound quality data so end users will receive the same sound quality every time they use their phone.

Helping boomers hear

Baby boomers are one population that could benefit from this personalization technique, Rader said. Many are cell phone users, and are experiencing reductions in hearing. Through the compression algorithm, "people in their 50s can receive 50 percent or more of speech signals lost to hearing impairments," Rader said.

Currently, Sound ID is porting its algorithm to Texas Instruments Inc.'s TMS320C54X family of DSPs. The algorithm requires 10 Mips of performance when running on these processors, Rader said. Sound ID is also porting its technology to TI's TMS320C55X family.

? Robert Keenan

EE Times

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