Understanding Hearing Loss - Part 2
By Professor W.P.R.Gibson. AM MD FRACS FRCS.


So what will happen in the next 20 years?

The cochlear implant will be fully implantable. The recipients will not have to wear any external speech processor. The whole unit will be surgically implanted. The head coil will only be worn to recharge the internal battery.

Already all the technology is available. There is a microphone which can be placed under the skin behind the ear. The only problem is the lack of a long life chargeable battery. At present the available batteries can only be recharged a few hundred times. Cochlear Pty, the company that makes the Australian cochlear implant is seeking a battery which can be recharged for a minimum of 7 years. After this time, the recipient can either revert to the head coil as used today or would have to have another surgery to replace the unit.

It is inevitable that the sound provided by the cochlear implant will become better and better. At present it is only indicated when the person has become so deaf that they cannot hear clearly on a telephone with either ear. Within the next decade, the cochlear implant will be indicated for people with a severe hearing loss.

Hearing aids will also improve. We have already seen the changes that digital hearing aids can provide. But this is only a beginning. If somebody has short or long sight, they expect that their spectacles will provide near normal vision. The quality of the sound provided by next generations of digital hearing aids will allow the users to hear sound as clearly as a person who uses spectacles to see.

The technology to distinguish speech in a noisy environment is already beginning. The use of directional microphones which focus automatically on the major sound source may one day provide the hearing impaired person with better hearing in noise than a normal ear. The size of the hearing aid will remain a choice for the user. As hearing aids will work better and better, the stigma of being seen wearing a hearing aid will lessen. Not everyone will feel it is necessary to cram the whole unit deep inside the ear canal. Perhaps this is why I have some reservations about surgically implanted hearing aids. A fully implantable hearing aid has been available. There was such a device developed in Germany. It is called the TICA (totally implantable cochlear amplifier) made by a company called Implex. The device is surgically implanted in an operation similar to the cochlear implant surgery.

The microphone is placed under the skin in the ear canal and the other lead had a vibrating probe which is placed directly on to the incus within the middle ear.

The technology at present is too expensive and liable to breakdown. The company has become insolvent. Nevertheless it is inevitable that a fully implantable hearing aid will reappear and become a viable option for those people who do not want any visible sign of their hearing loss.

The bone anchored hearing aid or BAHA has been developed to help people who have a conductive hearing loss and cannot wear a conventional hearing aid. Recently in Sydney, I implanted a young girl aged 12 years, called Vanessa, who was born without any ear canals. Despite several surgeries, it has not been possible to re-establish her ear canals and she had to wear a headband which pressed a bone conductor transducer hard against her scalp. The surgery consists of placing a titanium screw into the skull bone and thinning the surrounding scalp. After several months, the titanium becomes integrated into the bone and it is possible to couple the hearing aid to the screw by a simple press stud action. The recipient can wear the unit with no pressure on the scalp and the unit is comfortable, almost invisible, and provides excellent sound.

I have been able to start offering BAHA surgery to suitable candidates at The Royal Prince Alfred Hospital in a joint venture with Australian Hearing. Over the next year, it is hoped that 10 people will be able to receive this technology. There are adults who have had bilateral mastoid surgery who cannot wear a conventional hearing aid without causing the ear canal to become infected. By wearing a BAHA, these adults will save considerably on the expense of having their ears continually cleaned out by an ENT specialist and the expense of antibiotics and ear drops.

The NSW minister of Health, The Hon Craig Knowles has announced that NSW will begin a universal neonatal hearing screening program. From December 2002, every child born in a public hospital which has a birthing rate of over 400 per annum will be tested for a hearing loss prior to discharge. Smaller hospitals will be able to refer the babies for testing within a few weeks of discharge. Private hospitals will almost certainly offer similar services.

The testing will be done using automated auditory brainstem responses (AABR). The testing can be done by midwives and other staff who have taken a special course. It is estimated that 2500 babies will fail this preliminary test and will be referred for a second test about 4-6 weeks later. The second test will be done in specialised centres which have audiologists who can perform more accurate ABR testing. About 170 of these children will be found to be profoundly deaf - too deaf to benefit from a conventional hearing aid.

There are some major ethical issues which will have to be addressed.

The counselling of the parents will be critical. Imagine learning that your new baby is too deaf to ever be able to speak! Their new baby must learn to sign or will have to undergo surgery to receive a cochlear implant. What a dilemma for the new parents to face!

Nevertheless, the technology to allow their child to hear and to speak is now available and will improve over the lifetime of the child. Every child born deaf, even those with other significant disabilities, has the opportunity of learning to listen and speak effectively using either a hearing aid or a cochlear implant - if this technology is commenced within the first two years of life.

At the moment over 90 per cent of deaf children are born to hearing parents. These parents will almost always choose speech for their child. So what will happen to the 10 per cent of babies born to Deaf parents? Sign will become a less and less favourable choice. If 90 per cent of newly discovered deaf children have been chosen to use speech as their only form of communication, then number of Deaf people in NSW will become less and less.

An adult who is born deaf who only learns sign is likely to be on a disability pension during their lifetime whereas a deaf child who speaks has almost the same employment opportunities as a child born hearing and is likely to be a taxpayer. Can a Deaf parent chose sign for their child when technology is available to allow that child to learn to speak and listen so effectively? The problem is that there is only a limited period during the first few years of life when speech can be acquired. What will that child feel when he or she learns that speech was an option when younger but by learning only to communicate using sign, their educational, social and employment opportunities have been restricted?

Twenty years ago we could have hardly dare to dream of the changes which have occurred. Over the last 20 years we have seen digital hearing aids, bone anchored hearing aids and cochlear implants completely change the outlook for children and adults. Who would have dared to guess that congenital deafness could be so effectively managed? It is the first major disability which can be completely overcome by technology and new teaching techniques.

I hope that the Deaf Community will be able to accept and embrace the changes that technology brings. King Canute was unable to stop the tide coming in and the tide of change in hearing technology is also unstoppable. We must open our doors and hearts to all deaf people regardless of their method of communication.

This article posted to this web site on 11 September 2003