People who use hearing aids often complain that the devices are useless in crowded noisy places. Now, a team of Dutch researchers at Delft University of Technology may have solved the problem with a pair of hearing eyeglasses.

Each arm of the eyeglass frame has an array of four tiny directional microphones. Project leader Rinus Boone says the design allows users to hear in a more natural way. "When you [set the control] on 'high directivity' it [produces] a calm atmosphere where you only have loud sounds from the direction you are looking. Usually that is the [individual] with [whom] you are having a conversation."

Boon says the hearing glasses work like normal spectacles with some additional hardware. "You put on the glasses and there is a small connector which fits on the arms of the spectacles and which connect(s) to a very tiny loudspeaker," he says. "From there on we have an air tube that goes to the ear, which is like [a behind the ear hearing aid] which guides the sound through it to the ear."

The hearing glasses - which run on batteries and can be recharged at night much like a mobile phone - are currently on the market in the Netherlands under the trade name Varibel.