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It is easier to understand hearing loss if you understand how the ears work. The ear is made up of three main parts, known as the outer, middle, and inner ear.
Outer Ear: Sound waves travel through the air and first enter the body through the outer ear. The part of the ear that can be seen outside the body is called the pinna. The pinna collects and funnels sound into the auditory (ear) canal. The auditory canal is like a tunnel. It makes the sound louder and directs it toward the middle ear.
Middle Ear: The eardrum separates the outer ear from the middle ear, a chamber that is normally filled with air. Inside the middle ear are three tiny bones (ossicles) that form a chain connecting the eardrum to the opening of the inner ear. Sound waves cause the eardrum to vibrate. These vibrations cause the three tiny bones in the middle ear to move, transmitting the sound to the inner ear.
Hearing loss that occurs in the outer or middle ear is called a conductive hearing loss. This means that the hearing loss is due to a problem in transmission of sound from the air to the inner ear. An example of this would be changes in hearing because of fluid collection in the middle ear. Sometimes this happens when people have ear infections. The fluid “muffles” the sound when it is traveling through the middle ear.
Hearing loss that results from damage to the inner ear or auditory nerve is called sensorineural hearing loss. An example of this would be damage to the sensory hair cells in the inner ear from chemotherapy. Even though sound waves still move through the inner ear fluid, they can no longer be changed into nerve impulses, so the sound does not reach the brain. Sensory hair cells that process high-pitched sounds are usually damaged first, followed by damage to the sensory hair cells that process lower pitched sounds.
Radiation to the ear or brain can cause inflammation or ear wax buildup in the outer ear, problems with fluid buildup in the middle ear, or stiffness of the eardrum or middle ear bones. Any of these problems can result in conductive hearing loss. Radiation can also damage the sensory hair cells in the inner ear, causing sensorineural hearing loss. Damage from radiation may affect one or both ears, depending on the area of radiation treatment.
Platinum chemotherapy and aminoglycoside antibiotics damage sensory hair cells in the inner ear, causing sensorineural hearing loss. Most often, the effect is similar in both ears and is permanent.
How often hearing should be tested
Once at entry into long-term follow-up (at least two years after completion of cancer therapy).
If problems are detected, repeat yearly until stable.
If there is evidence of progressive hearing loss, test more frequently as needed, until stable.
30 Gy (3000 cGy) or higher
Yearly for 5 years after completion of cancer treatment (and if younger than 10, continue yearly testing until reaching age 10). Then:
-If no hearing problem is detected, test every 5 years.-If a hearing problem is present, test at least yearly or as recommended by a hearing specialist.
Less than 30 Gy (3000cGy)
Once, at entry into long-term follow-up (at least 2 years after completion of cancer therapy).
Repeat as needed if problems are detected.
Aminoglucoside antibiotics or loop diuretics
If there is any suspicion of a hearing problem, test at least once following completion of therapy.
When hearing loss is detected, it is important to have an evaluation by an audiologist or otologist (doctor who specializes in hearing disorders). Hearing loss can have a significant impact on a person’s ability to communicate and carry out daily activities. Younger children are at significant risk for school, learning, and social difficulties and problems with language development. It is therefore very important for a person with hearing loss to find the services and assistance that will best help to maximize their potential to communicate effectively. There are many options available, and these can be used in various combinations, depending on the hearing problem.
Hearing aids make sounds louder. Several types are available, depending on the age and size of the person and the extent of hearing loss. Most children under age 12 wear a behind-the-ear model to allow for adjustments as the child grows. These are available in a variety of colors – allowing for personalization and assisting with the child’s acceptance of the hearing aid. Teenagers and adults may benefit from a smaller, in-the-ear or in-the-canal model. It is very important that the hearing aid batteries are fresh and that the hearing aid is turned to the “on” position when in use.
Auditory trainers (also known as “FM trainers”) are devices that are particularly useful in the school setting. The person who is speaking (usually the teacher) wears a microphone that transmits sound over FM radio waves. The person with hearing loss wears a receiver that picks up the sound. This device can be worn alone or attached to the hearing aid and allows the person with hearing loss to hear the speaker clearly, even in a noisy environment.
Other assistive devices are also available for people with hearing loss. These include telephone amplifiers and teletypewriters (TTYs – sometimes also referred to as Telephone Devices for the Deaf or TDDs). Specialized appliances designed for people with hearing loss include alarm clocks that vibrate and smoke detectors with flashing lights. Closed captioning for television is widely available. The Internet is also a helpful communication tool for people with hearing loss, providing options such as email, online discussions, and access to information via websites. Newer pagers offer text messaging, instant messaging, Internet access, and photo transmission.
Telecommunication relay services are available in video and voice/text formats. The video relay service is internet-based and allows a person using signed language to communicate via a video interpreter, who translates the signed language into voice or text. The voice/text relay service allows a person using a teletypewriter to communicate through an operator, who then relays the message to the hearing person in spoken form.
Cochlear implants may be an option for people with profound hearing loss who are unable to benefit from hearing aids. These electronic devices are surgically placed behind the ear and electrodes are threaded into the inner ear. A microphone and speech processor are then used to transmit sound to the electrodes, stimulating the auditory nerve and allowing sound perception by the brain. After the cochlear implant is placed, auditory training is given for a period of time to teach the individual to recognize and interpret sounds.
Alternate or supplementary communication methods, including speech reading, sign language, and cued speech, are available for people with significant hearing loss. Spoken language may also be an option, but usually requires an intensive educational approach with speech therapy. In the United States, healthcare organizations that receive federal funding are required to provide sign language interpreters when requested by a patient.
If you have experienced hearing loss or received therapy that has the potential to damage your hearing, you should discuss this with your healthcare provider. Be sure to obtain prompt evaluation and treatment for ear infections, swimmer’s ear, and earwax impaction. Whenever possible, ask your healthcare provider to consider alternatives to medications that have the potential to cause further hearing loss, including aminoglycoside antibiotics, loop diuretics, salicylates (such as aspirin), and chelating agents (such as deferoxamine).
You should also take care to protect your ears from loud noises that can cause significant damage to your ears. Examples of items and activities that can be hazardous to your hearing include:
Construction workers, farmers
Boating or water skiing
Motorcycling or four-wheeling
Yard trimmers or leaf blowers
Cab, truck, and bus drivers