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.
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.
During your visit an audiometric exam will be conducted. This exam will determine if you have a hearing loss and if it’s correctable by hearing aids. If you have a hearing loss and it is determined that it cannot be corrected with hearing aids, you will then be referred out to an otolaryngologist. An otolaryngologist is a physician who specializes in ear, nose, and throat disorders and will investigate the cause of the hearing 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 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.
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.
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. With your Hearing Care Professional present, practice putting in and taking out the aid, cleaning it, identifying right and left aids, and replacing the batteries. Ask how to test it in listening environments where you have problems with hearing. Learn to adjust the aid’s volume and to program it for sounds that are too loud or too soft. Work with your Hearing Care Professional until you are comfortable and satisfied.
Proper maintenance and care will extend the life of your hearing aid. Make it a habit to:
An audiologist is a licensed professional who has a masters or doctoral degree in audiology. Audiologists are clinically, academically and professionally trained to determine which hearing losses require medical referral and/or assistive listening devices. Audiologist’s often focus on diagnosis and pediatric patients.
Hearing instrument specialists are also qualified trained and licensed to evaluate hearing and fit hearing aids. Their focus is on treating sensorineural hearing loss (hearing loss related to inner ear) and they are often more experience in fitting hearing aids.
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…
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!
You may experience some of the following problems as you adjust to wearing your new aid.
There is some new technology that is available for patients who have mild to moderate hearing loss who have larger canals. They are called ITE or In the Ear. These hearing aids fit deeply in the canal, are invisible, and are often best suited for patients with concerns about visibility.