Causes of deafness

All noise damages the hearing system in a similar manner. The ear is made up of three parts: the outer ear (pinna or auricle); the middle ear, which includes the eardrum (tympanic membrane); and the inner ear (cochlea) which is shaped like a snail shell and lined with tiny hairs.

Hearing loss occurs when the hairs inside the cochlea are damaged or die, which is a common occurrence as people age. Hair cells, which pick up sound waves and transform them into nerve impulses that are passed to the brain, do not regenerate. That's why most hearing loss is irreversible.

Symptoms of deafness

Many people don't realise they're going deaf. Our own built-in defences and ability to adapt makes it difficult to self-diagnose.

First you begin to lose the subtleties of language and find it hard to hear in situations where there is background noise. Then you find it hard to hear the television or while you're talking on the phone and with further hearing loss you have difficulty hearing one-to-one conversations.

You might be damaging or over-exposing your ears if you notice any of the following symptoms after listening to extreme sound on your MP3 player, Walkman or Discman:

• Voices suddenly sound muffled and are hard to understand.
• You experience ringing, buzzing or fluttering in one or both ears (this is known as tinnitus).
• Your ears hurt after being in a loud place.
• Your ears are suddenly super sensitive to noise.

If so, stop using the player and have your ears checked by a registered audiologist.

You can't get it back again

There's a widely held perception that hearing aids will compensate for hearing loss as effectively as glasses correct optical problems. They won't. Your ears have been permanently damaged and because the "connection" has been broken it's impossible to restore clear hearing. With a hearing aid you can expect the noise to be louder, but still muddy.

"That's why they are called assisted listening devices - because they don't bring it back to normal again," Research Engineer Warwick Williams says.

Williams would like to see a public education programme on the dangers of noise exposure similar to those used to highlight the dangers of sunburn, smoking, drugs and sexual habits.

Audiologists we spoke to opposed limiting an MP3 player's decibel output - as happens in Europe where they are capped at 100 decibels by law. Most preferred an effective education programme. In New Zealand two companies - Apple and Sony - have introduced devices to limit their players' decibel output. But it's up to the consumer to take the initiative.

Experts warn that, unless prevention of hearing loss becomes a health priority, a considerable portion of health funding will have to be spent on hearing loss rehabilitation.

Government assistance

There is a universal hearing aid subsidy for adults who aren't eligible for funding from ACC, Environmental Support Services or the War Pensions Scheme. This part-subsidy of $500 per hearing aid ($1000 for the pair) is available every five years to people with hearing loss.

That's a paltry sum if you consider hearing aids range from $1200 up to $7000 a pair. The subsidy doesn't cover the cost of batteries, and there is no increase in the subsidy if better technology is recommended by your audiologist.