Hearing aids are small electronic devices that you select with the help of your hearing professional. They are worn in or behind your ear. They amplify sound so that a person with hearing loss can listen, communicate, and participate more fully in daily activities. Hearing aids can help people hear better in both quiet and noisy situations. However, only about one out of five people who would benefit from a hearing aid actually use one.
A hearing aid has three basic parts: the microphone, amplifier and receiver (speaker). The hearing aid receives sound through the microphone, which converts the sound waves to electrical signals and sends them to the amplifier. The amplifier increases the power of the signals and then sends them to the ear through the receiver.
Hearing aids are primarily useful in improving the hearing and speech comprehension of people who have hearing loss that results from damage to the small sensory cells in the inner ear, called hair cells. This type of hearing loss is called sensorineural hearing loss. The damage can occur as a result of disease, aging, or injury from noise or certain medicines.
A hearing aid magnifies sound vibrations entering the ear. Surviving hair cells detect the larger vibrations and convert them into neural signals that are passed along to the brain. The greater the damage to a person’s hair cells, the more severe the hearing loss, and the greater the hearing aid amplification needed to make up the difference. However, there are practical limits to the amount of amplification a hearing aid can provide. In addition, if the inner ear is too damaged, even large vibrations will not be converted into neural signals. In this situation, a hearing aid would be ineffective.
If you think you might have hearing loss and could benefit from a hearing aid, visit your physician, who may refer you to an otolaryngologist or audiologist. An otolaryngologist is a physician who specializes in ear, nose, and throat disorders and will investigate the cause of the hearing loss. An audiologist is a hearing health professional who identifies and measures hearing loss and will perform a hearing test to assess the type and degree of loss.
Hearing aids work differently depending on the electronics used. The two main types of electronics are analog and digital.
Analog aids convert soundwaves into electrical signals, which are then amplified. Analog devices are can be adjusted or programmed to meet the needs of each user. This is done by your hearing professional. The use of analog processing in hearing aids is virtually extinct today.
Digital aids convert soundwaves into numerical codes, similar to the binary code of a computer, before amplifying them. Because the code also includes information about a sound’s pitch or loudness, the aid can be specially programmed to amplify some frequencies more than others. Digital circuitry gives a hearing professional more flexibility in adjusting the aid to a user’s needs and to certain listening environments. These aids also can be programmed to focus on sounds coming from a specific direction. Digital circuitry can be used in all types of hearing aids.
The hearing aid that will work best for you depends on the kind and severity of your hearing loss. If you have a hearing loss in both of your ears, two hearing aids are generally recommended because two aids provide a more natural signal to the brain. Hearing in both ears also will help you understand speech and locate where the sound is coming from.
You and your hearing professional should work together to select a hearing aid that best suits your lifestyle and needs, and that also fits your budget. Style and features can affect cost and the most expensive hearing aid may not always be the best suited device for you.
A hearing aid will not restore your normal hearing. With practice, however, a hearing aid will increase your awareness of sounds and their sources. You will want to wear your hearing aid regularly, so select one that is convenient and easy for you to use.
Before you buy a hearing aid, ask your hearing professional these important questions:
- What features would be most useful to me?
- What is the total cost of the hearing aid?
- Is there a trial period to test the hearing aids?
- What fees are nonrefundable if the aids are returned after the trial period?
- How long is the warranty?
- Can the warranty be extended?
- Will loaner aids be provided when repairs are needed?
- What instruction and services will the hearing professional provide?
Hearing aids take time and patience to use successfully. Wearing your aids regularly will help you adjust to them.
Become familiar with your hearing aid’s features. Work with your hearing professional until you are comfortable and satisfied
Proper maintenance and care will extend the life of your hearing aid. Make it a habit to:
Keep hearing aids away from heat and moisture.
Clean hearing aids as instructed. Earwax and ear drainage can damage a hearing aid.
Avoid using hairspray or other hair care products while wearing hearing aids.
Turn off hearing aids when they are not in use.
Replace dead batteries immediately.
Although they work differently than the hearing aids described above, implantable hearing aids are designed to help increase the transmission of sound vibrations entering the inner ear. A middle ear implant (MEI) is a small device attached to one of the bones of the middle ear. Rather than amplifying the sound traveling to the eardrum, an MEI moves these bones directly. Both techniques have the net result of strengthening sound vibrations entering the inner ear so that they can be detected by individuals with sensorineural hearing loss.
A bone-anchored hearing aid (BAHA) is a small device that attaches to the bone behind the ear. The device transmits sound vibrations directly to the inner ear through the skull, bypassing the middle ear. BAHAs are generally used by individuals with middle ear problems or deafness in one ear. Because surgery is required to implant either of these devices, many hearing specialists feel that the benefits may not outweigh the risks.
Hearing aids are generally not covered by health insurance, although most companies will have some forms of financing available. Financing is usually available. For eligible children and young adults ages 21 and under, Medicaid will pay for the diagnosis and treatment of hearing loss, including hearing aids, under the Early and Periodic Screening, Diagnostic, and Treatment (EPSDT) service. Also, children may be covered by their state’s early intervention program or State Children’s Health Insurance Program (SCHIP).
Medicare does not cover hearing aids for adults. However, diagnostic evaluations are covered if they are ordered by a physician for the purpose of assisting the physician in developing a treatment plan.
Researchers are looking at ways to apply new signal processing strategies to the design of hearing aids. Signal processing is the method used to modify normal sound waves into amplified sound that is the best possible match to the remaining hearing for a hearing aid user. NIDCD-funded researchers also are studying how hearing aids can enhance speech signals to improve understanding.
In addition, researchers are investigating the use of computer-aided technology to design and manufacture better hearing aids. Researchers also are seeking ways to improve sound transmission and to reduce noise interference, feedback, and the occlusion effect. Additional studies focus on the best ways to select and fit hearing aids in children and other groups whose hearing ability is hard to test.
Another promising research focus is to use lessons learned from animal models to design better microphones for hearing aids. NIDCD-supported scientists are studying the tiny fly Ormia ochracea because its ear structure allows the fly to determine the source of a sound easily. Scientists are using the fly’s ear structure as a model for designing miniature directional microphones for hearing aids. These microphones amplify the sound coming from a particular direction (usually the direction a person is facing), but not the sounds that arrive from other directions. Directional microphones hold great promise for making it easier for people to hear a single conversation, even when surrounded by other noises and voices.
The most common complaint a hearing impaired person will say is “I hear you, but I don’t understand you.”
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 hearing loss in both ears and you are a hearing aid candidate in both ears, you should wear two hearing aids. You have two ears because you need two ears. If we try to amplify sound in only one ear, you cannot expect to do very well. Even the best hearing aid will sound “flat” or “dull” when worn in only one ear.
Localization (knowing where the sound came from) is only possible with two ears. Localization is not just a sound quality issue; it may also be a safety issue. Think about how important it is to know where warning and safety sounds (sirens, screams, babies crying, etc) are coming from. Using both ears together also impacts how well you hear in noise because binaural hearing permits you to selectively attend to the desired signal, while “squelching” or paying less attention to undesired sounds such as background noise.
People cannot hear well using only one ear. There are studies in the research literature which show children with one normal ear and one “deaf” ear are ten times more likely to repeat a grade as compared to children with two normally hearing ears. Additionally, we know that if you have two ears with hearing impairment, and you wear only one hearing aid, the unaided ear is likely to lose word understanding ability more quickly than the ear wearing the hearing aid.
Binaural hearing allows a quality of “spaciousness” or “high fidelity” to sounds, which cannot occur with monaural (one ear) listening. Understanding speech clearly, particularly in challenging and noisy situations, is easier while using both ears. Additionally, using two hearing aids allows people to speak with you from either side of your head – not just your “good” side!