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December 11, 2002

New hearing implant software allows deaf to enjoy music

From: The Age, Australia - 11 Dec 2002

December 11 2002

The profoundly deaf may soon be able to understand the subtleties of tonal languages and even appreciate a Mozart concert, thanks to new hearing implant software developed in Australia.

The new cochlear technology, developed by Dr Robert Fearn of the University of NSW, allows the hearing impaired to pick up frequencies not available to them with conventional implants.

People who are profoundly deaf can currently hear speech using a conventional cochlear implant, a miniaturised hearing aid, originally developed by Melbourne researchers and now used by more than 30,000 people around the world.

But the problem with conventional implants is they cannot distinguish between the tonal subtleties necessary for appreciating music or understanding languages in which tonal variation can change the meaning of words such as Chinese or Thai.

Fearn likened wearing a conventional implant to "having a piano with 22 keys" instead of the 88 used - making it difficult to play or hear Fur Elise, for example.

"Now people can hear speech, they say they want to hear music," Fearn, who has a background in electrical engineering, told ABC Science Online.

An implant consists of an array of miniature electrodes surgically inserted into the cochlear, an area of the internal ear where hearing is conducted.

These electrodes carry out the function of hair cells which normally stimulate auditory nerves in response to sound, but which do not function in the profoundly deaf.

Sound collected by an external microphone and a signal processor is converted to electrical impulses which are then delivered by radio link to the cochlear.

Depending on which frequency band the sound falls into, particular electrodes will stimulate particular nerves, enabling the wearer to hear high or low tones.

As part of his research, Fearn discovered the stimulation of nerves in different locations of the cochlear could give the same pitch, as long as the nerves were stimulated at different rates.

Not only this, but different combinations of the nerve being stimulated and the rate of stimulation could give a different quality of sound for the implant wearer.

In this way, Fearn's study of people wearing cochlear implants has not only developed more sensitive implants - it has contributed to the fundamental understanding of how the human ear works.


Copyright © 2002 The Age Company Ltd