Published: Oct. 1, 2008
Updated: Oct. 1, 2008
David M. Kaylie, MD, FACS
Duke University Medical Center
Otolaryngology – Head and Neck Surgery
Benee Connelly, AuD
Duke Otolaryngology of Raleigh
Hearing impairment is very common – it affects 10% of all Americans.
Two million are deaf and 26 million have some degree hearing loss (over half of these are 65 or older). With an aging population, the problem of hearing loss will only become greater.
The cost of hearing impairment is $56 billion annually -- 50 percent higher than the cost of visual impairments. The high cost comes from everything from disability payments to missed work days.
Worldwide, the problem is even worse: China and India are in a dire situation with a disproportionate number of deaf people because of poor access to medical care and frequent use of toxic antibiotics, or those that cause hearing impairment.
Hearing loss is a major problem that will affect most people at some point – including yourself or a loved one. A large population in the US will go untreated or remain unaware of their treatment options, so public education is key to understanding hearing health.
The ear is comprised of the ear canal, ear drum, hearing bones (ossicles), and the inner ear. These parts work together to make up the two kinds of hearing that we have: conductive and sensorineural.
Sound is collected by the outer ear and which sends the waves down the ear canal to the ear drum. As the ear drum vibrates, the three hearing bones (commonly known as the hammer, anvil, and stirrup) begin to vibrate. The third bone, the stirrup, stimulates the inner ear.
When the third ear bone moves, it moves in and out like a piston, in the cochlea, which is the hearing part of the inner ear. The spiral-shaped cochlea is filled with fluid that conducts the sound wave up and then back down.
The cochlea is arranged sort of like a guitar, where the top of it is responsible for picking up the lowest sounds and the bottom picks up the highest tones. (So the waves travel to both areas to make sure all tonal range is picked up)
The inner ear has nerve cells, called hair cells, that bend as the sound wave travels by – which in turn triggers the nerve to fire. Most hearing loss is caused by something that has damaged the hair cells – normal aging, noise, and some medications can all damage hair cells.
There are two main types of hearing loss:
Presbycusis is the normal hearing loss that occurs with aging. It is the most common form of sensorineural hearing loss and will affect half of people over the age of 75. Men are affected twice as often as women.
The symptoms of adult hearing loss are slowly progressive hearing loss, usually in both ears; and ringing in the ears (tinnitus) which is a sign of nerve damage – usually occurring in both ears and presents with a variety of tonal qualities.
The causes of presbycusis include:
All hearing loss should be evaluated by an ENT doctor. He will look for common problems that can cause hearing loss, but which exclude true hearing loss:
An ENT will also perform a thorough hearing test to determine exactly what kind of hearing loss you have.
The best ways to prevent hearing loss are:
There is no surgery or medicine that can treat nerve-related hearing loss, so we must rely on amplification and assistive devices.
Chronic noise exposure causes a very typical pattern of hearing loss. Someone with hearing loss has trouble hearing speech over background noise -- all they can hear is background noise.
Hearing loss in just one ear really needs to be evaluated – causes can just be conductive hearing loss because of infection, otosclerosis, hole in drum, or middle ear fluid.
People who have nerve hearing loss in only one ear have asymmetric neural hearing loss – the vast majority of the time it’s just how you are, but it could be also a tumor (acoustic neuroma), or it could be the result of a stroke or multiple sclerosis.
A 2006 duke study showed that effects of hearing loss include depression, strained relationships with family and friends, and deterioration of basic well being. In addition, 26 million Americans have hearing loss, but only 20 percent who could benefit from a hearing aid actually have one.
All hearing aids have four basic components:
No. Ten years ago you had analog aids only, which are currently being phased out – they converted waves into electrical signals but amplified everything equally instead of distinguishing between sounds.
Digital hearing aids are today’s aids – they come in many price points, and are superior in quality, programming and features or options. They translate sound to digital code – so the manufacturer can write specific programming software to be used in certain situations. A digital hearing aid analyzes and adjusts sounds based on your level of hearing loss and listening needs. It also producse high quality sound that is extremely accurate, clear and distortion free.
Special features available on digital aids include:
Yes. If you have loss in both ears two aids provide for a more natural perception of sound. They will provide better understanding in background noise, make it easier to determine the direction of the sound, and will slow deterioration of hearing.
Hearing aids will not restore hearing to normal, nor will they prevent further decline, but can provide substantial benefit.
The best hearing aid is not the smallest, least expensive, or most invisible. You should pick one that suits your needs and lifestyle – what are your listening needs, what type of hearing loss do you have, how severe is your hearing loss. And, style and features do affect cost.
The only people qualified to conduct a hearing test are a physician or ENT, an audiologist, a technician, or a hearing instrumentation specialist.
Audiologists are required to be licensed by the state. They must have doctoral degree, proof of 90 clock hours in university study, and 1800 hours of supervised time on the job.
Hearing instrument specialists must have at least a high school diploma and have worked at least 30 hours per week for 50 weeks in the setting of sale and fitting of hearing aids. They also must document that they have been supervised for 750 hours on the job.
The FDA restricts the sale of hearing aids to those who have received a proper medical evaluation. Your audiologist is required to have documentation of the evaluation prior to selling you a hearing aid.
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