Hearing Glasses

May 2000

Our more mature readers will probably remember the combination glasses and hearing aids that some folks used many years ago. What would you think if I told you that they're baaa-aack??

Well, not exactly!! But, researchers at the Department of Acoustic Imaging and Sound Control at the Technical University of Delft in the Netherlands have just put the finishing touches on a prototype pair of 'hearing glasses'.

Two of the big problems with current hearing aids are that (1) they can't differentiate between desired sounds and undesired sounds, and (2) they can't tell the direction a particular sound is coming from. These two issues are often related, in that the desired sounds are often coming from a particular direction. Placing a hearing aid microphone so that it favors sounds from the front over those from the back takes advantage of that relationship. But scientists can only do so much with a single microphone.

That's one of the advantages that some of the personal FM systems offer - like Phonak's MicroLink system, for example. The transmitter has a switch that allows the user to select Omni or Directional. Omni picks up sounds equally from all directions, while directional favors the direction that the device is pointed. The Directional setting is the same idea as pointing the hearing aid microphone towards the front, but a more effective way to do it. I don't know exactly how Phonak does it in their system, but one very effective way to do this is to use multiple microphones.

That's exactly what the hearing glasses do. They have four microphones in each arm of the glasses. Each arm also has a processor that combines the signals from the four microphones to produce one signal that is sensitive almost exclusively to sound coming from the front. The integrated signal is sent to a coil located in the earpiece. The coil in the glasses drives the telecoil (T-coil) in a person's hearing aids.

The developers estimate that the 'hearing glasses' are at least two years from commercial production. They are confident that the cost will be reasonable.

For additional information, visit www.rnw.nl/science/html/hearing20000314.html.