How’s your Hearing—What??
Dan Onion, MD, MPH
Mt. Vernon/Vienna Health Officer
This column is largely about public health issues, i.e. issues that have a general population health impact. Most often those involve the prevention of diseases with direct or indirect effects beyond the individual to at least portions of the rest of the population, as immunizations do. Last month I wrote about sleep, which has only indirect public health implications resulting from sleepy people driving home from work or elsewhere, or generally not being their best. Mt. Vernon’s John Olson thanked me for the insights it gave him and suggested I might write about hearing loss as a sequel. The only public health issues there are in the possibilities in preventing or diminishing the afflictions; nevertheless, I suspect hearing loss is of interest to many, so here goes!
Deafness is a relatively rare condition until people reach retirement age. Sure, a few youngsters suffer it, but by the time people reach age 70, nearly half of them are significantly deaf by formal testing. Deafness rapidly develops in most of the other half over the next 2 decades; well over 90% over 90 suffer have hearing loss, according to epidemiologic statistics. That number seems a little high to me, but many with the disease hide it well; for instance, they start agreeing with me after the first repeat, even though they have no clue what I just said. So, my impression of how many have significant hearing loss, is undoubtedly an undercount.
Almost all deafness is due to injury or blockage of both ears. Thank the Lord we are given two ears by evolution, so knocking out one ear is only a minor inconvenience. Here is how hearing works. Each ear is made up of 3 parts:
•External ear, the ear lobe and canal
•Middle ear (the ear drum, ear bones, and the air-filled space drained by the Eustachian tubes to the back of the throat
•Inner ear, very complicated, containing:
-Semi-circular canals, like 3 small gyroscopes lined with hair-cell, which, via the 8th cranial nerve, alert the brain where little sand grains inside each canal land, in 3 dimensions, to tell you where you are in relation to gravity
-Cochlea, another long, coiled tube like a snail shell, also lined with hair cells that are twitched by each different frequency in the normal hearing range, low to high, roughly 0.5-2.5 cps [cycles per second, or “Hertz”)
Deafness is caused predominantly by presbycusis, Greek for “old hearing”, which means the cumulative effects of aging on hearing, almost always from recurrent exposure to loud (at or over 85 decibels) noise, be it music, chain saws, or many other things you can imagine. That level is a consensus of professionals, although there are no national standards or clinical trials (not surprising, since who would volunteer to be a subject in a study where they might be subjected to high decibel noise daily for many years, to see what happens!) Loud noise repeatedly hitting the middle C hair cell in the cochlea, causes that cell eventually to be damaged. The high-pitched hair cells above high C are the most sensitive to such injury. So, high pitch hearing is usually lost first. And because consonants provide a major part of word meaning, the loss of their whispery, high pitched sounds severely impacts a person’s ability to interpret other’s speech. Vowel sounds are in the 0.5-1.5 cps range and hence are lost much later. Manifesting very similarly is much rarer interference or damage to the auditory nerve from medicines, like the reversible ear-ringing caused by aspirin in moderately high doses (over 1 gm daily), permanently from some medicines, classically antibiotics, like streptomycins, or other diseases like Menniér’s Disease. These types of losses are all categorized as a Sensory-Neural (S-N) hearing loss.
The second most common contributor to presbycusis is ear wax in the external ear. Usually this normal mixture of dead skin, sweat and oil stays soft and leaks out of the canal on its own or with the help of warm water in dry climates like winter. But if it does not, it can build up into very firm, dark -brown plugs. Ineffective efforts to dislodge it with fingers, Q-tips or other tools can pack it even more firmly against the ear drum causing a “conductive” hearing loss. Ironically hearing aids do this very well too. Older people have less oily skin secretions and hence get this condition more easily. Usually it can be prevented by simply running warm water into the ear canals while bathing or showering. And for people with recurrent wax impaction and resultant conductive hearing loss, a family member can gain the skill of looking in there weekly or monthly to prompt more room temperature water irrigation with a bulb syringe and frequent ear drops to soften the impacted wax.
Clinicians can distinguish between S-N and conductive hearing loss by looking in the ear and with simple tuning fork tests called Rinné and Weber.
So, what can we do to help/cope?
•Avoid loud noise damage. Ear protectors work fine, though they can be uncomfortable on a hot summer day. Wear them or ear plugs, which I think are a little less good because they are harder to get a good fit. Make your nearly adult kids to protect their hearing at concerts or using machines; they may thank you decades later.
•Be sure you are not given medicines that can cause permanent damage unless you must have it to survive.
•Run bath water into your ear canals while bathing
• If wax impaction occurs, regularly check for impacted wax and irrigate the ears clear.
•Speak in low frequencies to presbycusis sufferers. Men’s voices work better than women’s; women can speak in their lowest voices. Don’t shout; that diminishes the clarity of consonants, which are crucial to understanding speech. Look at the person, so they can see your lips move; use confirming gestures. They can begin to learn lip reading that way.
•Hearing loss accompanies dementia often, and each makes the other worse. Isolation can be due to either, and accommodating hearing loss can slow progression of dementia.
•Hearing loss also causes depression; sufferers withdraw from contacts because of frustration with not being able to participate in conversations. Find ways to engage anyway.
•Many users experience “recruitment,” which is a condition where the useful loudness of sound lies in a very narrow decibel range. You may have spoken louder and louder to a deaf person who suddenly says “quieter, you don’t have to shout”; you know then that you overstepped their narrow range. The same can happen with a hearing aids.
•Use assistive devices, just as you would a cane with a bad set of knees. A cheap stethoscope in the sufferers’ ears and held toward you can markedly improve their understanding. Electronic devices are often available at churches, as they are for TV sets and telephones.
•Explore hearing aids, though beware, there are a lot of shysters out there. Get an evaluation at a hospital audiology center (MaineGeneral centers in Augusta and Waterville, and elsewhere). The problems with hearing aids are that they are moderately hard to keep working, especially with concomitant cognitive problems. They magnify all sounds, not just the ones you want to focus on. Aids can be very expensive, in the many $1000s.
So, practice prevention starting now, wherever you are on the hearing spectrum. Prevent ear wax build up if you or family members have a problem. Use assistive devices sooner rather than later.
Did I help, John?