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 | Hearing
By Michael Spilane, MD
Have a little trouble hearing when you're in a crowd? Maybe a lot? Do you find yourself frequently asking people to repeat themselves? You are not alone. Hearing loss is a significant problem for twenty-five percent of persons over age sixty-five, and for almost fifty percent of those over age eighty.
Hearing loss has a variety of causes, but the type that shows up in later years is nearly always sensorineural. The problem is degeneration of the nerve cells in the inner ear. In the normal ear, sound waves proceed through the outer and middle ear and then tickle tiny hairs that are attached to nerve cells in the cochlea of the inner ear. In sensorineural hearing loss, the hairs and nerve cells have been damaged and are unable to collect the vibrations and transmit sound messages to the brain.
Sensorineural hearing loss does have significant hereditary influences, but it most often occurs in persons with no family history of hearing problems. The best answer to the why question is not a very elucidating one it appears to be due to simple wear and tear. Some loss of hearing acuity can be demonstrated in almost all persons by age 50, but it is usually insufficient to cause trouble. As the years go by it becomes increasingly more likely that degeneration of the nerve cells will cause significant hearing symptoms.
Although most sensorineural hearing loss is related to heredity or to wear and tear over years, other factors may be causal or contributive. Loud occupational or recreational noise is very harmful to the nerve cells in the inner ear. With prolonged exposure, hearing loss is likely. These days the wise worker wears ear protectors in noisy environments. The unwise kids who like their music at 100 decibels are fodder for tomorrow's hearing aid companies.
Some drugs also have the potential to damage the ears nerve cells. The list of problem drugs is not long, but includes life-saving agents in the antibiotic and diuretic (water pill) groups. Aspirin and quinine can also cause trouble at high doses.
Not all nerve cells are affected equally in sensorineural hearing loss. Those that detect high frequency sound wavelengths are most prone to damage. And this is not a good thing. High frequency sounds are the ones that enable discrimination of speech sounds. Since they carry the consonants of speech, loss of high frequencies make the words sound like all vowels (A-E-I-O-U) and make the speaker sound mumbly. The words are heard but not understood. At least in the early stages of hearing loss, discrimination of the spoken words is more a problem than the volume of the speaker.
The nerve cells in normal ears have sufficient power to detect and separate specific conversation even when there is a lot of background noise. But the nerve-damaged ear is overwhelmed by background noise and separation is impaired. An early symptom of sensorineural hearing loss is trouble hearing conversation in the presence of background noise. Conversation in noisy places is lost, and the impaired person is likely to avoid such environments.
It is common for an older person to tolerate and adapt to hearing loss rather than seek professional help. But the toleration and adaptations typically lead to yet more problems. The impaired person may stop attending movies and plays, avoid dining-out with friends, sit mute in conversational groups, and avoid initiating conversation. At its worst, the progressive social isolation can lead to depression and even confusion. The absence of pain or acute distress, along with the insidious progression of the hearing loss, makes the afflicted person under-aware of the severity of the problem and its social consequences. Too often a spouse, friend or family member has to use the baseball bat approach to convince the deaf one to seek help.
Sound is one of the riches of life. Missing out on sound is missing out on life. Only about one in five people with hearing loss use a hearing aid. Cost, embarrassment and misinformation are the common reasons. In my next column I will discuss treatment of hearing loss and will review options available for hearing aids and hearing devices. Say what?
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