7.11: Disorders in Hearing

Presbycusis

Aging causes different degrees of hearing loss. Individuals who have lost a great deal of hearing because of aging are said to have presbycusis, which is the third leading chronic condition among those over age 65. Only arthritis and high blood pressure occur more frequently among the elderly.

The incidence of presbycusis increases exponentially with age. About 12 percent of those between ages 45 and 65 are affected. This increases to more than 24 percent for those age 65 to 74 and may reach 39 percent for those over age 75. The incidence among those in institutions is considerably higher, reaching 70 percent.

Both the percentage of cases and the seriousness of presbycusis are greater for men than for women. It is thought that greater hearing loss among men may be caused by noise associated with occupations traditionally held primarily by men. Presbycusis becomes progressively worse as the age of an affected person increases. This condition tends to run in families.

Presbycusis seems to result when the previously mentioned age changes in the cochlea and in neurons and brain areas involved in hearing occur to an unusually severe degree. Though some of these changes cause hearing loss of all sound frequencies, most cause hearing loss predominantly of higher‑frequency sounds.

Effects

Presbycusis reduces the ability of the ears to alert a person to desirable factors and harmful factors in his or her surroundings, hinders learning and communication, and reduces the enjoyment sound provides. Since presbycusis affects high‑frequency sounds most, it substantially reduces the ability to hear the quality of music called brilliance. Presbycusis makes understanding speech difficult primarily because many consonant sounds in words are high‑frequency sounds. High‑pitched voices become especially difficult to understand.

The increasing difficulty in understanding speech has diverse effects on people with presbycusis. For example, these people may fail to respond or respond incorrectly when others speak to them. Other people may begin to believe that the person is becoming demented. Both the people with this condition and others may feel that they are being ignored. Individuals with presbycusis sometimes believe that others are trying to deceive them or talk about them in demeaning ways and often tend to withdraw from social contacts. Depression and paranoia are not uncommon outcomes.

Presbycusis may also alter speaking ability because affected individuals can no longer hear their own voices well. People with presbycusis may become annoying because they sometimes talk very loudly.

Prevention and Compensatory Techniques

While presbycusis is at least partially due to aging, it seems that chronic exposure to loud sounds increases both the likelihood of developing it and the severity of the problems it causes. Therefore, avoiding exposure to loud sounds, such as loud music and noise from tools and machinery, may help prevent presbycusis. When loud sounds are unavoidable, earplugs or other protective devices should be used.

Though there is no cure for presbycusis, people can be helped to compensate for it. Hearing can be increased by raising the volume of sound, such as by talking louder, or by using amplifying hearing aids.

The probability that a particular person with hearing loss will benefit from the use of a hearing aid depends on several factors. These include the type of presbycusis or other condition (e.g., eardrum injury, middle ear infection) that produced the hearing loss, the nature and severity of the hearing loss, and the ability of the person to use a hearing aid. The evaluation for hearing aid use is best done by a qualified audiologist.

Reducing background noise, echoes, and the speed of speaking can also improve the understanding of what is heard. Individuals with presbycusis can be trained to do lipreading and use other visual cues to increase their ability to understand those who are speaking. Speakers can help by getting the listener's attention; facing the listener; using more gestures and facial expressions; speaking slowly and clearly; repeating; keeping their mouths visible; and asking for feedback to confirm the listener's understanding.

Tinnitus

Tinnitus is the perception of sound when there is no sound external to the person. Sometimes the perceived sound originates from within the body; in other cases there is no sound whatever. Until 1990, tinnitus was among the ten most common chronic conditions among the elderly. It has now been displaced to a lower rank because of the higher reported frequencies of visual impairment and varicose veins.

Tinnitus can result from many causes including obstruction of the ear canal; abnormality of any of the parts of the middle ear, inner ear, or eustachian tube; infection in the ear or CNS; tumor in the ear or CNS; high blood pressure; atherosclerosis; diabetes mellitus; hormone imbalances; malnutrition; migraine headaches; medications; and toxic chemicals.

In many cases of tinnitus, the sound being perceived is little more than a nuisance, although sometimes it becomes quite distracting. Tinnitus may alter or prevent normal sleep.

Eliminating tinnitus requires elimination of the cause. Individuals who cannot be cured can sometimes be helped by using low levels of other sounds as a distraction or cover for the tinnitus. Other treatments include dietary modifications (e.g., vitamin supplements, reduce caffeine), and surgery.