Q: Why do people become hard of hearing as they grow older?
A: The outer part of the ear channels sound waves into the ear canal. They then hit the eardrum, causing it to vibrate. These vibrations are then transferred to the tiny middle ear bones, which then cause fluid waves in the cochlea (a snail shaped, fluid-filled organ in the inner ear with tiny hair-like structures projecting into the fluid). These fluid waves make the hair cells move; this motion is then converted to electrical signals. These electrical signals are carried by the auditory nerve to the brain, where they are interpreted as the sounds we perceive.
Many age-related changes can compromise hearing, including:
* Functional limitations of the hair cells within the cochlea, usually beginning with limited ability to react to high frequencies.
* Atrophy of nerve cells in the cochlea, to and/or within the brain.
* Metabolic changes, for example changes brought on by high glucose levels in diabetics.
* Structural changes, such as those that may limit the ability of parts of the hearing system to vibrate normally.
Most age-related hearing loss is actually due to a combination of one or more of these factors (hair cell changes being the most common). Things that may increase the likelihood of age-related hearing loss include genetic predisposition, diabetes, poor circulation, side effects of certain medications, a history of repeated exposure to loud noises, smoking or various other causes.
Age-related hearing loss typically starts subtly and often with higher frequency sounds (so if your partner has a high-pitched voice, your hearing loss may actually begin with inability to hear their voice clearly) and slowly progresses over time. Patients typically note difficulty understanding when someone speaks to them, especially if there is background noise. They may frequently ask people to repeat themselves, play the TV loudly, have difficulty hearing when they talk on the phone, or may complain of ringing in their ears.
About 10 percent of people age 45 to 55 have symptomatic hearing loss; this grows to 25 percent of those aged 55 to 65, and almost 50 percent of people 65 to 85. Age-related hearing loss usually affects both ears, although the hearing loss is often more pronounced on one side.
To assess hearing loss, a healthcare provider will perform a history and physical exam (for example, to identify ear wax buildup that can be adding to the problem). Hearing testing (audiometry) will then be done to quantify the issue.
Presently, there are no medications or treatments to correct or reverse age-related hearing loss. However, options do exist to help patients function better:
* Hearing aids receive, process and then amplify sound, allowing the patient to better interpret what they hear, especially speech. However, as few as only one in seven people who would benefit from a hearing aid actually use one, mostly because of the perceived social stigma. This has created a revolution of hearing aid designs, including ones that are extremely small and sit behind the ear or in the ear canal (there is even an implantable hearing aid that has no external parts and cannot be seen at all). Some are digital rather than analog to allow enhanced sound processing to adjust for certain frequencies/situations.
* Other amplifying devices can help with telephone calls and in other situations.
* Bone anchored hearing aids translate sounds directly into vibrations that are then transferred to the skull bones, allowing the patient’s own hearing system to create electrical signals to be carried to the brain.
* For those with severe hearing loss, cochlear implants, which are small devices surgically implanted in the inner ear that directly send signals to the auditory nerve, may be an option. After implantation patients need to be “trained” to interpret the signals their brain receives, “translating” them into recognizable sounds.
Age-related hearing loss often worsens over time, possibly leading to complete hearing loss. This can cause problems ranging from decreased quality of life (such as by limiting social interactions causing isolation or by interfering with work) to dangerous situations (such as the inability to hear a fire alarm or a car’s horn).
Families and friends of hearing limited people can help in many ways. They can:
* Speak more loudly, without shouting.
* Face the hearing impaired person when speaking, enabling them to better utilize visual cues.
* Help minimize competing background noise, such as by turning off the radio to allow conversations in the car.
* Help with the costs of a hearing aid, since Medicare does not cover it.
More information can be found at the National Institute on Deafness and Other Communication Disorders website: http://www.nidcd.nih.gov/Pages/default.aspx.
Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com.