Space-Age Sound Comes Down To Earth

Digital signal processing used by NASA is now affordable

It's often difficult for anyone you call on a mobile phone to hear you clearly under the best of circumstances. And mobile calls are frequently made under the worst of conditions -- on street corners, from moving cars, in crowded malls. A new headset using advanced digital signal processing (DSP) technology can dramatically improve the quality of those calls.

The Jawbone headset, from Aliph, a Brisbane (Calif.) startup, is leading a wave of DSP-enabled consumer audio and imaging products. The technology, critical to CAT scans, customized hearing aids, and those spectacular photos from Mars, has been too exotic and expensive for the mass market -- and in some ways it still is. The Jawbone is priced at $149.95 (from and is somewhat bulky -- though attractive enough to win a silver in this year's BusinessWeek-sponsored Industrial Design Excellence Awards. But the relatively steep price is vindicated by a demonstration in which a Jawbone wearer's voice comes in over your cell phone as clear as can be, even though he's talking while running a gasoline-powered weed-whacker.

Conventional noise-canceling headsets, which have been on the market for some time, do a reasonable job of reducing some kinds of regular background sounds, such as the rumble of a car or the drone of your office ventilation system. The Jawbone, using an active noise-reduction system originally developed by Aliph for the military to use in armored vehicles, takes a different approach. It employs two microphones. One, which picks up vibrations from your jaw (hence the name), senses only your voice. The other picks up your voice and background noise. Some DSP magic compares the two and subtracts nearly all the noise, leaving only your voice. A switch turns the system on and off, letting the other party hear its amazing effectiveness.

THE JAWBONE CONSISTS OF TWO PARTS -- the earpiece and a belt-clip processing unit that sits in the middle of a long, somewhat bulky cable between the earpiece and the phone. Because the unit's processor needs to draw power from the cell phone, it requires a special plug. And so far models are available only for Nokia (NOK ), Motorola (MOT ), and Sony Ericsson phones. Both drawbacks, however, should be temporary. To keep costs down, Aliph built the Jawbone using off-the-shelf programmable DSP chips. Once it goes into volume production, the company should switch to cheaper, more efficient, and much smaller custom chips. Then all of the electronics and a battery could fit into a relatively lightweight earpiece.

Jawbone is in the vanguard of a wave of products using advanced DSP technology to improve digital sound and image quality. (Oddly enough, to a computer, a photo and a song represent much the same sort of data.)

Until now the most sophisticated signal processing has been the preserve of the military, scientific, and medical communities. That's changing fast. For example, a new line of Hewlett-Packard (HPQ ) cameras, starting with the Photosmart R607, uses advanced signal processing to analyze the lighting of a shot and improve the picture in the camera, eliminating much of the work that otherwise would be done on a computer. In essence, the technology NASA uses to enhance photos from space probes now comes in a $300 camera.

Devices such as HP's camera will become commonplace. Better DSP will also bring improved quality to media players of all sorts and to high-definition video transmitted wirelessly or over the Net. Today's signal compression takes a toll on quality. But when video signals can be fine-tuned with more powerful DSP, images will look better and consume less bandwidth. Similarly, we'll be able to stream CD-quality music over relatively slow wireless phone networks. Signal processing is an arcane technology that goes back to the dawn of electronic communications, but it's starting to make a big difference in everyday products.

By Stephen H. Wildstrom

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