Science can restore a sense of sight to th blind, even those who have never seen, Professor L. Kay, of Canterbury University's electrical engineering department, told the science students' conference in Christ-church.

All The Benefits of sight could be obtained through hearing, he said.

Professor Kay cited the bat, blind yet able to intercept its manoeuvrable prey, the moth, by using acute hearing, which picks up high frequency sound waves bounced off objects. The bat's brain has been developed to interpret the echoes in the same way as man interprets visual images.

Thus the bat "visualises" the object without analysing the sound. The insects, with their different shapes, give off a different sound pattern to the bat's ears.

The professor said that, although the bat is naturally able to receive and emit high-frequency sound waves, this does not prevent man from using his technology to improvise a similar system—and Professor Kay has been doing research on this.

"Torch"

Earlier a special "torch" had been used to give a blind person an idea of the distance from, and the number and composition of objects around him. Curves could be detected and objects such as windows and curtains differentiated from chairs and tables in these experiments, he added.

Although the "torch" principle was enthusiastically received by American societies for the blind, it could not simulate the perception of the bat as the sounds had still to be interpreted and were very restricted in range and direction.

Spectacles

Professor Kay said he eventually found the answer in a pair of spectacles, looking much like sunglasses, but which incorporated a transmitter and receiver on each side, passing separate signals to each ear.

By this stereophonic effect positions of objects could be noted from the varying frequencies of the signal to each ear. The brain could project the sounds in space to simulate vision by focusing the blind person's attention always on the field of vision ahead of him—virtually by making him use his eyes.

Professor Kay quoted a blind man who used the glasses after more than a year with the torch; his reactions: "Surely this must be like seeing!"

Professor Kay said even those still using the torches had no interest in seeing dogs or canes.

The torches are now in production, but the glasses are not yet available for general use, he added.

He noted that such research could be undertaken at a minimal cost if the researcher found pleasure in his work. He contrasted his expense of £750 with the American bill of £100,000 for fewer results.