Hearing Loss

Hearing loss occurs to most people as they age. Hearing loss can be due to the aging process, exposure to loud noise, certain medications, infections, head or ear trauma, congenital (birth or prenatal) or hereditary factors, diseases, as well as a number of other causes. In the year 2001, there are some 28 million people in the USA with hearing loss. Hearing loss is the single most common birth "defect" in America. Hearing loss in adults, particularly in seniors, is common.

Causes of Hearing Loss
The simplest cause of hearing loss is a build-up of wax in the ear canal. If this wax, otherwise called cerumen, completely blocks the ear canal, you might experience a very noticeable loss of hearing. Wax is produced naturally in the outer ear canal and some people produce much more wax than others. People who wear hearing aids may have an increase in the amount of wax in the ear canals since the hearing aid or earmold tends to reduce the amount of natural ventilation to the ear. Fortunately, in most cases, a physician can easily remove the earwax (either with a probe or by flushing with water).

Other items pushed too far into the ear canal, such as cotton can create the same effect. Even though some people do this in an attempt to clean the ear canal, the adage that says "you shouldn't put anything smaller than your elbow into your ear" should be followed. Using hairpins, match sticks or cotton swabs can cause the wax to be pushed deeper into the canal beyond the point where it will naturally leave.

A cold or sinus may cause you to experience some hearing loss. It is a slight fullness that should disappear when you get over the cold or infection. Often, if you fly or travel in the mountains, you may also experience a minor degree of hearing loss due to the difference in pressure between the air in the middle ear and the outside air. This problem usually will disappear if you blow your nose, swallow or chew gum.

Exposure to loud noise even for a short period can cause you to feel that your hearing ability is lessened and you may also experience some tinnitus (ringing in the ears). Called a 'temporary threshold shift', this usually goes away in time once you are out of the noisy environment. Too much exposure to loud noise can lead in time to a permanent hearing loss.

Living longer can result in some reduction in hearing ability. It is quite normal to experience a reduction in hearing ability, as we get older. It is estimated that on average one in ten people have some degree of hearing loss. Over the age of 60, the estimate changes to one in four and over the age of 70, to one in two. As we live longer, the chances that we will experience some reduction in our ability to hear is high. A common cause of conductive hearing loss (affecting the middle ear) is otosclerosis, which is a condition in which one of the small bones in the middle ear (the stapes in the ossicular chain) is affected with a bony growth. An operation called a stapedectomy may be performed to overcome this problem.

Infection in the middle ear can cause a build-up of fluid in the middle ear cavity leading to a temporary hearing loss and possibly a discharge from the ear. Perforations of the eardrum (tympanic membrane) can also lead to conductive hearing loss. Conductive hearing loss is usually medically or surgically correctable given the techniques and medications available today, however, sensori-neural hearing loss is usually irreversible. Sensori-neural hearing loss can be genetic or caused by a wide range of viral infections, such as measles, mumps or meningitis.

There are a number of drugs, which are ototoxic, which means that they are capable of damaging the hearing system. Some of these are powerful life-saving medications, but others are widely used remedies. Even aspirin, if taken in large quantities, can affect your hearing. Some drugs can cause tinnitus, so if you are taking medication that causes dullness in your hearing or noises in your head, inform your doctor. Some drugs will cause a temporary loss, but with others the loss could be permanent.

Accidents that involve head injuries may cause hearing loss due to damage to the nerves, which carry signals to the brain, or damage to the part of the brain that receives the auditory signals, called the auditory cortex. A blast may rupture the eardrum. Large changes in pressure experienced by divers may cause risk of hearing loss. A severe blow to the head might result in some reduction in hearing ability. If you suspect that you have a hearing loss, consult with your family physician and obtain a thorough hearing evaluation from an audiologist or ENT.

Degrees of Hearing Loss
Results of the audiometric evaluation are plotted on a chart called an audiogram. Loudness is plotted from top to bottom. Frequency, from low to high, is plotted from left to right. Hearing loss (HL) is measured in decibels (dB) and is described in general categories. Hearing loss is not measured in percentages. The general hearing loss categories used by most hearing professionals are as follows:

Normal hearing (0 to 25 dB HL)
Mild hearing loss (26 to 40 dB HL)
Moderate hearing loss (41 to 70 dB HL)
Severe hearing loss (71 to 90 dB HL)
Profound hearing loss (greater than 91 dB HL)

Types of Hearing Loss
The external and the middle ear conduct and transform sound; the inner ear receives it. When there is a problem in the external or middle ear, a conductive hearing impairment occurs. When the problem is in the inner ear, a sensorineural or hair cell loss is the result. Difficulty in both the middle and inner ear results in a mixed hearing impairment (i.e. conductive and a sensorineural impairment). Central hearing loss has more to do with the brain than the ear, and will be discussed only briefly.

Conductive hearing loss occurs when sound is not conducted efficiently through the ear canal, eardrum, or tiny bones of the middle ear, resulting in a reduction of the loudness of sound that is heard. Conductive losses may result from earwax blocking the ear canal, fluid in the middle ear, middle ear infection, obstructions in the ear canal, perforations (hole) in the eardrum membrane, or disease of any of the three middle ear bones.

A person with a conductive hearing loss may notice that their ears may seem to be full or plugged. This person may speak softly because they hear their own voice quite loudly. Crunchy foods, such as celery or carrots, sound very loud and this person may have to stop chewing to hear what is being said. All conductive hearing losses should be evaluated by an audiologist and a physician to explore medical and surgical options.

Sensorineural hearing loss is the most common type of hearing loss. More than 90 percent of all hearing aid wearers have sensorineural hearing loss. The most common causes of sensorineural hearing loss are age related changes and noise exposure. A sensorineural hearing loss may also result from disturbance of inner ear circulation, increased inner fluid pressure or from disturbances of nerve transmission. Sensorineural hearing loss is also called "cochlear loss," an "inner ear loss" and is also commonly called "nerve loss." Years ago, many professionals said there was nothing that could be done for sensorineural hearing loss – that is totally incorrect today. There are many excellent options for the patient with sensorineural hearing loss.

A person with a sensorineural hearing loss may report that they can hear people talking, but they can’t understand what they are saying. An increase in the loudness of speech may only add to their confusion. This person will usually hear better in quiet places and may have difficulty understanding what is said over the telephone.

Central hearing impairment occurs when auditory centers of the brain are affected by injury, disease, tumor, hereditary, or unknown causes. Loudness of sound is not necessarily affected, although understanding of speech, also thought of as the "clarity" of speech may be affected. Certainly both loudness and clarity may be affected too.

What To Do If You Think You’ve Lost Some Hearing
If you believe that sounds are not as loud as you need them to be, or if speech is muffled, it is a good idea to first, have your ears checked by your family physician or by a medical ear specialist called an otologist or otolaryngologist to check for wax in the ear canals, infection or treatable disease.

If your problem can be treated medically or surgically, pursue that treatment. If this is not possible, or if after treatment, you still have some difficulty hearing, investigate hearing aids and the other aids available to you. Be certain that your physician gives you a signed statement or form saying that your hearing loss has been medically evaluated, called a "medical clearance", and that you may be considered a candidate for hearing aids. Law requires this form before a hearing aid dispenser can provide you with a hearing aid. Adults over 18 may sign a waiver of this regulation but it is recommended for your best hearing health that you not sign a waiver but obtain a medical check up first.

Then get your hearing tested to determine how much hearing loss you have. Get a complete hearing evaluation from a Certified Clinical Audiologist with a Certificate of Clinical Competence in Audiology (CCC-A) issued by the American Speech Language and Hearing Association (ASHA). ASHA is the professional association, which regulates and governs the field of audiology. Do not confuse the CCC-A degree with the description used by many hearing aid dealers of "Board Certified" which is granted by the National Hearing Aid Society (NHAS). NHAS is a trade association of hearing aid dealers.

Audiologists can measure your hearing ability and identify the degree of loss. They can design and direct a rehabilitation program, recommend and fit the most appropriate hearing aid fittings and measure the hearing improvement from the use of hearing aids. They will provide guidance and training on how to use your new hearing aids and recommend the use of other assistive technology, if appropriate, and teach speech reading. They can help you to find solutions that reduce the effects of hearing loss by working with your spouse, family, employer, teacher, caregiver or other medical specialists. In addition, audiologists evaluate balance, vertigo and dizziness disorders. If amplification (hearing aids) is recommended, do not hesitate to pursue the trial of such instruments. Be certain to arrange for such trial (at least 30 days) and purchase of hearing aids through a facility, which will assist you in becoming oriented to the new experience of hearing with amplification. Remember that it is a learning experience and does require time, practice and patience.

Last revised April 4, 2002
Source: ‘Hear What You’ve Been Missing’ by Donna S. Wayner, Ph.D.
Hearing Healthy Website: www.healthyhearing.com