[Editors] MIT: Using touch to help deaf people

[Elizabeth Thomson]

http://web.mit.edu/newsoffice/2009/deaf-touch-0226.html


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MIT: Using touch to help deaf people
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For Immediate Release
THURSDAY, FEB. 26, 2009

Contact: Elizabeth A. Thomson, MIT News Office
E: thomson at mit.edu, T: 617-258-5402

Photo Available

CAMBRIDGE, Mass.--Lip reading is a critical means of communication for  
many deaf people, but it has a drawback: Certain consonants (for  
example, p and b) can be nearly impossible to distinguish by sight  
alone.

Tactile devices, which translate sound waves into vibrations that can  
be felt by the skin, can help overcome that obstacle by conveying  
nuances of speech that can’t be gleaned from lip reading.

Researchers in MIT’s Sensory Communication Group are working on a new  
generation of such devices, which could be an important tool for deaf  
people who rely on lip reading and can’t use or can’t afford cochlear  
implants. The cost of the device and the surgery make cochlear  
implants prohibitive for many people, especially in developing  
countries.

“Most deaf people will not have access to that technology in our  
lifetime,” said Ted Moallem, a graduate student working on the  
project. “Tactile devices can be several orders of magnitude cheaper  
than cochlear implants.”

Moallem and Charlotte Reed, senior research scientist in MIT’s  
Research Laboratory of Electronics and leader of the project, say the  
software they are developing could be compatible with current smart  
phones, allowing such devices to be transformed into unobtrusive  
tactile aids for the deaf.

“Anyone who has a smart phone already has much of what they would need  
to run the program,” including a microphone, digital signal-processing  
capability, and a rudimentary vibration system, says Moallem.

Sensing vibrations

Tactile devices translate sound waves into vibrations that allow the  
user to distinguish between vibratory patterns associated with  
different sound frequencies. The MIT researchers are testing devices  
that have at least two vibration ranges, one for high-frequency sounds  
and one for low-frequency sounds.

Using such handheld devices, deaf people can more easily follow  
conversations than with lip reading alone, which requires a great deal  
of concentration, says Moallem.

“It’s hard to have a casual conversation in a situation where you have  
to be paying attention like that,” he says.

Current prototypes can be held in the user’s hand or worn around the  
back of the neck, but once the acoustic processing software is  
developed, it could be easily incorporated into existing smart phones,  
according to the researchers. To lay the groundwork for such future  
applications, the researchers are investigating the best way to  
transform sound waves into vibrations.

Existing tactile aids have been in use for decades, but the MIT team  
hopes to improve the devices by refining the acoustic signal  
processing systems to provide tactile cues that are tailored to boost  
lip-reading performance, says Reed.

As part of their project, the researchers have done several studies on  
the frequency reception ability of the skin. The human ear can  
perceive frequencies up to 20,000 hertz, but for touch receptors in  
the skin, optimal frequencies are below 500 hertz.

Using a laboratory setup with a device that can provide distinct  
vibration patterns to three fingers simultaneously, Moallem has done  
preliminary studies of deaf people’s ability to interpret the  
vibrations from tactile devices.

This project was originally inspired by earlier studies Reed did on  
the Tadoma technique, a communication method taught to deaf-blind  
people. Practitioners of that method hold their hands to someone’s  
face while they are talking, allowing them to feel the vibrations of  
the face and neck.

Reed’s study, done about 20 years ago, showed that the deaf-blind  
subjects could successfully understand speech with this method —  
especially if the other person spoke clearly and slowly.

“We were inspired by seeing what deaf-blind people could accomplish  
just using the sense of touch alone,” says Reed.

This research is funded by the National Institute on Deafness and  
Other Communication Disorders.

--END--

Written by Anne Trafton, MIT News Office
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