+== acb-l Message from Penny Reeder <[log in to unmask]> ==+
>From the newsroom of The New York Times, New York, Thursday, September 27,
2001 .....

A Hearing Aid Points to the Sound

By YUDHIJIT BHATTACHARJEE

WHEN a mobile phone starts ringing, most people can find it fairly quickly -
under a cushion, inside a handbag, behind a bookcase, wherever.

Most people, but not all, because all do not have normal hearing. For the
hearing-impaired, turning in the direction of a friend saying hello can be
challenging enough, even with the most sophisticated hearing aids.

Hearing aids amplify sounds, but they provide little information about where
the sounds are coming from. That is why people with hearing aids often don't
know which way to look when they hear a sudden screeching of brakes on the
street or a balloon bursting at a birthday party.

A Swedish research team is working to remedy that handicap by using a
technology similar to the one used for locating submarines in naval warfare.
The researchers have designed a system that enables the user to determine
the direction that any particular sound is coming from. The device could be
helpful to people with severe visual impairment as well as a hearing
problem.

This sound localizer developed by the research team, led by Dr. Erik Borg at
the Orebro Medical Center in Orebro, Sweden, is a combination of microphones
and vibrators fitted onto a pair of eyeglasses. Sound waves picked up by the
microphones are analyzed by a computing device in a way similar to how the
human ear processes sound. People with normal hearing localize sounds by
perceiving differences in key features like intensity and the time the sound
reaches the left and the right ear. The device follows the same principle,
with an arrangement of three microphones serving as a substitute for the
ears.

Once the system computes the direction of the sound source, it sends a
signal to two vibrators attached at each side of the eyeglass frame. The
vibrators, little pads mounted on soft springs, touch each temple. The
gentle drumming of the pads upon the skin enables the user to sense the
direction from which the sound is originating.

"A short pulse in the left vibrator means the user should look to the left,"
Dr. Borg said in a telephone interview. "A long pulse on the same side means
the user should look behind the left shoulder. We have similar vibration
codes for sounds coming from directly ahead and behind."

The researchers have so far tested the device on a small group of deaf and
deaf- blind subjects. In all the tests, users were able to identify the
direction of sounds from loudspeakers located in different places in a room.

"This is pioneering work that could provide improved mobility and safety to
thousands of people," said Dr. James J. DeCaro, a professor at the National
Technical Institute for the Deaf at Rochester Institute of Technology.

The researchers say it could be at least three years before the device will
be ready to be used in a natural environment. The current version of the
localizer is linked wirelessly by a portable radio system to a PC that
analyzes the sound waves and relays the data to the microphones. "That's
O.K. to work with in the lab," Dr. Borg said. "We will eventually need to
have a programmed chip anchored in the eyeglasses."

Makers of the device are trying to reduce the number of vibrators in the
design from two to one to cut down on its power requirement. The localizer
could then work with a miniature battery fitted in the eyeglass frame.

A single vibrator, however, would make it difficult to communicate
directional information to the user. "The advantage of having two vibrators
on either side of the head is that the codes for `left' and `right' are
intuitive," Dr. Borg said.

Hearing-impaired people interviewed by the researchers said that they most
needed sound-localizing assistance to figure out the direction from which
people and vehicles are approaching them and link sounds to appliances in
the kitchen.

The researchers are now working to equip the sound localizer with the
ability to identify each of these sounds. The next step would be to develop
specific vibrational codes corresponding to them. With a code for each
sound, users would be able to recognize sounds from different patterns of
tremors felt upon the skin.

"The sound of footsteps, for example, would be felt by a specific pattern,"
said Lennart Neovius, an engineer on the research team. "Likewise, we could
assign different patterns for the sound of a car engine, the buzz of a
toaster and so on. The idea is to use the sense of touch to provide
hearing-impaired people with a detailed picture of their environment."

Those who would most benefit from the wide-ranging sensory input envisioned
by Dr. Borg and his colleagues include victims of Usher's syndrome, who are
born deaf and suffer a decreasing field of vision over time.

"Sounds around us are loaded with information," said Sergei Sorokin, a
manager at Mo Gard, a rehabilitation center for the deaf-blind near Orebro.
"If deaf-blind people could sense even a part of that, it would make a big
difference to their quality of life."

Copyright 2001 The New York Times Company


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