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Although the military signal is periodically degraded to prevent unauthorized uses, the research team devised a way to get continued accuracy by comparing the satellite signals with a stationary land-based signal. Whenever the distances between the two readings differ, they correct the satellite signal accordingly.

The virtual display is based on the work of Dr. Klatzky's main collaborator, Dr. Jack Loomis, a perceptual psychologist at the University of California at Santa Barbara. Dr. Loomis has studied the auditory cues the brain uses to compute the location of the source of the sound. Since the distance between a distant point and each of the ears is slightly different, the brain uses the difference in time that a sound arrives at each of the ears to calibrate how far away it is and in which direction.

Dr. Klatzky's research has focused on the ability of blind people to navigate. Earlier studies had cast doubt on the ability of blind people to orient themselves in a room unaided when given minimal cues about the location of things. But in a series of tests -- like having a person walk two lengths of a triangle, then asking him or her to take the shortest path back to the beginning -- Dr. Klatzky found that blind people fared about as well as sighted people who were blindfolded.

These tests "gave us confidence our navigation system would not be useless because of some deficiency of the blind in finding their way around," Dr. Klatzky said.

The research also draws on the expertise of Dr. Golledge, a geographer with a research specialty in psychological issues, such as how people construct mental maps of their surroundings. Dr. Golledge became blind about 10 years ago from a degenerative disease of the optic nerve, but continues to teach and do research. Looking for Right Mix

One goal of the research team is to miniaturize the navigation system's components so they will be lighter and less conspicuous, worn in a waistpack with wires to earphones.

Another goal is to find the optimal mix of spoken markers to give the person using the system. "The question is, how many objects should talk to you at a given time?" Dr. Klatzky said. "If you walk down a street, dozens of objects may call to you, but too many will overwhelm your memory and attention capacity. Learning a new layout may demand a more general level, while just getting down the street might require a more detailed chorus of voices."

Other questions under investigation include details like the point at which a landmark down the road should start announcing itself, and the most useful phrases to use.

In a report to be published in the proceedings of the first annual Conference on Assistive Technologies, which will be held in Marina del Rey, Calif., in October, the Santa Barbara researchers say they hope one day their navigation aid will instill in those who use it "feelings of independence and confidence that are lacking in all but the most adventurous of blind travelers."

Even so, Dr. Golledge also uses his cane on test voyages, just to be sure no surprises block his path. Dr. Klatzky said: "We don't envision this system as entirely relieving the need for a Seeing Eye dog or cane. They'll still be needed to be sure about obstacles like moving cars that aren't on the computer's map."

Photo: Dr. Reginald Golledge testing navigation system for blind. (Kim Reierson) Diagram: "Talking Maps" Signals from Global Positioning System satellites are relayed to antenna and coordinated with computerized of immediate environment. Blind jperson hears obstacles identify sounds or words. Electronic compass indicates head position, so computer knows what sounds to send to each year. (Source: Carnegie Mellon University) (pg. C9)