When Fred Kawabata contracted shingles in 1997, naturally he was concerned. But the last thing he expected was for the virus to permanently knock his sense of balance off kilter, and when the infection attacked the vestibular nerves in his ear, that's what happened.
"When it first struck me i was flat on my back. I had vertigo, I was dizzy, I could hardly get out of bed, and I was that way for a couple of weeks," he recalls. "In about a month, I could get up and walk around although it was still very uncomfortable. It took a couple months before I could be reasonably comfortable walking around. [Now], when I'm walking on a flat surface, I generally don't have to think about it very much. But if I'm on an uneven surface like when I'm hiking and the trail is rough, then I really have to think about it."
Now he and others like him could be helped by a new device created by Marco Dozza and his colleagues at Oregon Health and Science University. Worn like a personal music player, it has sensors that detect when a person tips outside a vertical "safe zone." Specialized musical tones tell them if they've tipped too far in one direction or another, and they can correct their posture.
"Because of the character of the tones that they've chosen it was quite intuitive to determine my position," says Kawabata. "The left and right was indicated by the stereo effect and the forward and back had a different character. It was very easy to learn quickly."
Scientists call this "biofeedback," and Dozza set up an initial pilot study to measure its effect. He had nine people with balance disorders stand on a pillow with their eyes closed. With the musical tones they stayed within the safe zone nearly three times longer than they could without them. His results were published in Archives of Physical Medicine and Rehabilitation.
"Audio feedback was compensating for the vestibular information they were missing," Dozza explains. "With this device we could really see a big improvement and we could really see that they were more stable. This was an improvement you can see with your eyes. You don't need an instrument to measure it."
Dozza will continue testing the device under different conditions, and thinks people with balance problems might only have to use it for a short period in the morning to "tune up" their senses for the rest of the day.