"Skin" to aid hearing

Nov 30 2009

An apparatus that converts sound to vibrations makes it possible for individuals who are deaf and blind or severely hearing impaired to perceive and recognize sounds with their skin. The method, which can also be adapted for infants, has been developed by engineering researcher Parivash Ranjbar, who is submitting his findings in a new dissertation at örebro University in Sweden.

Above all, individuals who are both deaf and blind are a vulnerable group that find it difficult to understand what is going on in their surroundings. But the new aid, which has been named "Monitor," enables them to distinguish different kinds of sounds, such as voices, telephones, birdsong, cars, thunder, rain, and wind.

"After brief training, one of my trial subjects could even understand what was being said in a conversation," says Parivash Ranjbar.

Converted to lower frequencies
The apparatus works by registering sounds and converting them to lower frequencies that the skin can perceive as vibrations, without the sound losing its distinct character. While human hearing can perceive sound frequencies between 20 and 20,000 Hz, the skin cannot sense frequencies higher than 800 Hz. Moreover, the skin cannot distinguish between sounds that are too close to each other.

"The deaf-blind already have an acquired ability to glean information from vibrations. For example, they can recognize the step of different individuals through the vibrations in the floor, or feel the vibrations from a pot when the water starts to boil. But with Monitor, they have entirely new possibilities of keeping up with what's going on in their surroundings, and this makes them feel much more secure."

Easy to use
When Parivash Ranjbar had a group of deaf-blind people test the apparatus, they managed to identify a large portion of the sounds, both in the home and outdoors.

"It was easy for the trial subjects to learn to use it, even for those who were born deaf and therefore have no sound library to fall back on."

Monitor, which is small enough for people to carry with them everywhere, consists of a microphone that picks up sounds, a processor that converts them, and a vibrator part that conveys them. The vibrator can also be mounted in pacifiers and bottle nipples to provide infants born without hearing with a chance to become familiar with sounds through their lips and perceive what is going on around them.

Early learning
"Learning early is a great advantage. This also gives parents the possibility of communicating with their babies through their voices, which is especially important if the child is also blind."

"Many more aids can be developed using this technology, such as helping people who are deaf and blind to ride horseback, using vibrations that communicate their position on a track. I'm constantly getting new ideas when I see the needs and possibilities actually exist," says Parivash Ranjbar.

SOURCE Audiological Research Center, örebro