Explaining Hearing Loss
Prevalence of Hearing Loss
Approximately 31.5 million people in the U.S. have some degree of hearing loss. This number is expected to increase as the baby boomer generation ages. 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. Hearing loss is the single most common birth “defect” in America as approximately 2-3 out of 1,000 infants is born with some type of hearing loss. Hearing loss in adults, particularly in seniors is very common due to the aging process.
How Do I Know If I Have Hearing Loss?
You may have hearing loss if:
- You hear people speaking but you have to strain to understand their words.
- You frequently ask people to repeat what they said.
- You don’t laugh at jokes because you miss too much of the story or the punch line.
- You frequently complain that people mumble.
- You need to ask others about the details of a meeting you just attended.
- You play the TV or radio louder than your friends, spouse and relatives.
- You cannot hear the doorbell or the telephone.
- You find that looking at people when they speak to you makes it easier to understand.
If you have any of these symptoms, you should see an audiologist to get an “audiometric evaluation.”
An audiometric evaluation (AE) is the term used to describe a diagnostic hearing test, performed by a licensed audiologist. An AE is not just pressing the button when you hear a “beep.” Rather, an audiometric evaluation allows the audiologist to determine the type and degree of your hearing loss, and it tells the audiologist how well or how poorly you understand speech. After all, speech is the single most important sound, and the ability to understand speech is extremely important.
The AE also includes a thorough case history (interview) as well as visual inspection of the ear canals and eardrum. The results of the AE are useful to the physician should the audiologist conclude that your hearing problem may be treated with medical or surgical alternatives. Written hearing tests, “dial a hearing test” and other online hearing tests are not particularly accurate and are certainly not diagnostic tests, but may be utilized as screening tools. These screenings are usually free and can be scored within a few seconds. Written hearing screenings may point the patient (or consumer) in a particular direction and may help validate that a hearing problem may indeed exist.
Degree 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.
The types of hearing loss include:
- Conductive Hearing Loss
- Sensorineural Hearing Loss
- Central Hearing Impairment
 Conductive Hearing Loss
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. Patients with a conductive hearing loss should be evaluated by an audiologist and a physician to explore medical and surgical options.
 Sensorineural Hearing Loss
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 disturbances of inner ear circulation, increased inner fluid pressure or from disturbances of nerve transmission. Sensorineural hearing loss is also referred to as “cochlear loss”, “inner ear loss” and most commonly “nerve loss”.
Years ago, many professionals said there was nothing that could be done for sensorineural hearing loss; this is not correct with today’s technology. There are several excellent options for the patient with sensorineural hearing loss. A person with a sensorineural hearing loss may report that he/she can hear people talking, but 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
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 or “clarity” of speech may be affected. Certainly loudness and clarity may be affected, too.
Hearing Impairment in One Ear
A hearing impairment that is confined to one ear prevents a person from distinguishing the direction of sound. He will also have difficulty hearing from the involved side and may find it difficult to understand words in a noisy background or where the acoustics are poor. When this impairment is secondary to a middle ear problem (i.e, conductive), surgery will usually be possible to restore the hearing, giving a better auditory balance. When the impairment is sensori-neural (i.e., hair cell loss), it is often possible to restore some of this hearing balance through the use of a hearing aid.
A complete audiologic/otologic examination is necessary to determine what type of hearing impairment is present, its probable cause and its treatment. The treatment of choice may be remedial, preventive, medical, surgical or a combination of these. Each person with impaired hearing should have the benefit of adequate auditory rehabilitation.
A well rounded program of rehabilitation for persons with a hearing loss may include speech reading, auditory training, speech strategy techniques, instruction in the use of a hearing aid and guidance in social adjustment. All aspects of the program do not necessarily apply to each individual with impairment, but each individual may be helped through some of these methods.