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Hearing loss is a normal and often unavoidable part of aging, with 40 percent to 50 percent of people over 60 years of age suffering from some degree of impairment.

But compared to vision problems or other sensory deficits, hearing loss can be difficult to identify and often goes undetected.

Unfortunately, hearing deficits that are not confronted can interfere with important social interaction and cause emotional turmoil and stress.

Those who recognize and acknowledge the signs of hearing loss will find that modern technological advances offer a new world of assistance for those with hearing difficulties.

Hearing loss that is specifically associated with advancing age is known as presbycusis. It is this gradual, progressive, high-frequency hearing loss that is hardest to detect.

Many will insist that they hear well, even if they have great trouble understanding speech. This is because they can usually hear the intensity of sounds well, but have trouble distinguishing among the "high-frequency" or consonant sounds.

Presbycusis is believed to be caused by the natural and irreversible deterioration of the sensory part of the ear, as well as a loss of sensory cells and nerves in the nervous system.

Many doctors believe that exposure to excessive noise may speed up the breakdown.

Besides age-related presbycusis, there are two general types of hearing disorders.

Conductive hearing loss disorders, which block the normal transmission of sound waves from the eardrum to the sensory apparatus, are not particularly common in older individuals. Causes include severe ear infections, disease or trauma to the outer or middle ear. Some types of conductive hearing loss are correctable.

Sensorineural hearing loss is caused by problems with the inner ear or auditory nerves. It may be a result of brain tumors, hemorrhage into the brain or other types of disease.

Many believe that exposure to certain types of drugs, most notably antibiotics and diuretics, can cause or increase sensorineural hearing impairment. Mixed hearing loss is a combination of the two.

Anyone who suspects even minor hearing loss should report it to a doctor without delay. In most cases, patients will be tested with pure tone audiometry after the ears have been cleared of earwax — which itself can be a factor in hearing loss, reducing sound intensity by as much as 35 percent.

Once hearing impairment is discovered, a good hearing aid can amplify sound and improve speech perception for anyone with minor to severe sensorineural hearing loss. The problem is that many people resist wearing them regularly.

Maybe they don't know that today's updated offerings are more convenient, less obvious and more effective than ever before. Best of all, hearing aids can maximize communication and understanding — ensuring that a hearing-impaired person is able to actively participate in professional, social and family activities without any annoying barriers.

Impressive multiprogrammable hearing instruments have been in use for several years. They are programmed to suit each user's ear by a trained audiologist. A remote control unit stores several different programmed prescriptions for particular environments. The touch of a button easily adjusts the hearing aid to a noisy concert, a restaurant, a quiet picnic in the country or other environment.

Contemporary improvements over conventional hearing aids are significant. Users can easily discern speech despite the usually taxing background noise. And the devices can be reprogrammed as hearing loss changes with time.

Other assistive hearing devices also help the impaired to function more easily in home and public environments.

*Infrared and FM broadcasting in public buildings: These systems make it easier for the hearing impaired to discern speech in auditoriums, theaters, courthouses and other public spaces.

A microphone is placed close to the sound source and the signal is carried to the receiver via light waves or radio frequencies. The person receives the signal with special headphones — minus background noise and other confusing distractions.

*Home entertainment: Infrared systems can also amplify sound from television, and closed-caption decoders provide additional assistance.

*Telephone amplifiers: Most telephone companies will provide assistive devices free if a doctor has certified that an individual is hearing impaired. Sound amplifiers, louder bells and lights that flash when the phone rings can all improve telephone communication.