What is presbycusis?
Presbycusis is the loss of hearing that gradually occurs in most individuals as they grow older. Hearing loss is a common disorder associated with aging. About 30-35 percent of adults between the ages of 65 and 75 years have a hearing loss. It is estimated that 40-50 percent of people 75 and older have a hearing loss.
The loss associated with presbycusis is usually greater for high-pitched sounds. For example, it may be difficult for someone to hear the nearby chirping of a bird or the ringing of a telephone. However, the same person may be able to hear clearly the low-pitched sound of a truck rumbling down the street.
There are many causes of presbycusis. Most commonly it arises from changes in the inner ear of a person as he or she ages, but presbycusis can also result from changes in the middle ear or from complex changes along the nerve pathways leading to the brain. Presbycusis most often occurs in both ears, affecting them equally. Because the process of loss is gradual, people who have presbycusis may not realize that their hearing is diminishing.
What are the symptoms of presbycusis?
With presbycusis, sounds often seem less clear and lower in volume. This contributes to difficulty hearing and understanding speech. Individuals with presbycusis may experience several of the following:
- The speech of others seems mumbled or slurred.
- High-pitched sounds such as “s” and “th” are difficult to hear and tell apart.
- Conversations are difficult to understand, especially when there is background noise.
- A man’s voice is easier to hear than the higher pitches of a woman’s voice.
- Certain sounds seem annoying or overly loud.
- Tinnitus (a ringing, roaring, or hissing sound in one or both ears) may also occur.
What are the causes of presbycusis?
Sensorineural hearing loss is caused by disorders of the inner ear or auditory nerve. Presbycusis is usually a sensorineural hearing disorder. It is most commonly caused by gradual changes in the inner ear. The cumulative effects of repeated exposure to daily traffic sounds or construction work, noisy offices, equipment that produces noise, and loud music can cause sensorineural hearing loss. Sensorineural hearing loss is most often due to a loss of hair cells (sensory receptors in the inner ear). This can occur as a result of hereditary factors as well as aging, various health conditions, and side effects of some medicines (aspirin and certain antibiotics).
Presbycusis may be caused by changes in the blood supply to the ear because of heart disease, high blood pressure, vascular (pertaining to blood vessels) conditions caused by diabetes, or other circulatory problems. The loss may be mild, moderate, or severe.
Sometimes presbycusis is a conductive hearing disorder, meaning the loss of sound sensitivity is caused by abnormalities of the outer ear and/or middle ear. Such abnormalities may include reduced function of the tympanic membrane (the eardrum) or reduced function of the three tiny bones in the middle ear that carry sound waves from the tympanic membraine to the inner ear.
What can be done?
Much of the hearing loss caused by noise exposure can be prevented. Awareness of potential sources of damaging noises, such as firearms, snowmobiles, lawn mowers, leaf blowers, woodworking machinery and loud appliances is important. Ear plugs or special fluid-filled ear muffs can give protection and should be worn to help avoid the possibility of damage to hearing. Excessively loud everyday noises, both at home and at work, can pose a risk to a person’s hearing. Avoiding loud noises and reducing the amount of time one is exposed to everyday noises may be helpful.
There are many strategies to help people with presbycusis. Hearing aids may be recommended for some individuals. Assistive listening devices can provide further improvement in hearing ability in certain situations. One example of such a device is the built-in telephone amplifier. Another example is FM systems that make sounds clearer, with or without a hearing aid, by delivering sound waves like a radio. Training in speechreading (using visual cues to determine what is being spoken) can help those with presbycusis to understand better what is being said in conversations or presentations.
If you have a hearing loss caused by presbycusis or know someone who does, share these tips with family members, friends, and colleagues.
- Face the person who has a hearing loss so that he or she can see your face when you speak.
- Be sure that lighting is in front of you when you speak. This allows a person with a hearing impairment to observe facial expressions, gestures, and lip and body movements that provide communication clues.
- During conversations, turn off the radio or television.
- Avoid speaking while chewing food or covering your mouth with your hands.
- Speak slightly louder than normal, but don’t shout. Shouting may distort your speech.
- Speak at your normal rate, and do not exaggerate sounds.
- Clue the person with the hearing loss about the topic of the conversation whenever possible.
- Rephrase your statement into shorter, simpler sentences if it appears you are not being understood.
- In restaurants and social gatherings, choose seats or conversation areas away from crowded or noisy areas.
How does hearing work?
- The outer ear collects sound waves and works like a funnel to send them through a narrow tube (ear canal) that leads inside the ear. At the end of the ear canal is the eardrum (tympanic membrane).
- The tympanic membrane is a thin membrane that vibrates when sound waves strike it. It divides the area called the outer ear from the middle ear. It is attached to a set of three tiny bones in the middle ear.
- These bones are called the hammer (malleus), anvil (incus), and the stirrup (stapes). The bones pass the vibrations of sound waves to a small organ in the hearing part of the inner ear called the cochlea, which is a coiled structure like a snail shell.
- The inner ear is filled with a thin fluid that transmits pressure changes throughout the cochlea. Inside the cochlea are tiny hair cells that pick up sound vibrations from the fluid and cause nerve impulses in the auditory nerve.
- The auditory nerve carries the message to the brain, where it is interpreted as sound.