What Are Hearing Aids?
Hearing aids are electronic devices used to improve hearing. Hearing aids allow patients to
- Hear sounds they have been unable to hear previously
- Hear speech more clearly, particularly over the phone
- Communicate more easily with others
- Communicate more easily in noisy situations such as large groups or loud environments
Most types of hearing aids have similar parts:
- A microphone that detects sound
- An amplifier that helps increase the sound volume
- A miniature speaker that sends the amplified sound into the ear canal
- Batteries to power the unit
What Are Hearing Aids Used For?
Most types of hearing impairment can be improved with use of hearing aids. Unlike eyeglasses which can restore 20/20 vision, hearing aids do not restore hearing to 100% normal, but they can improve hearing by about 50% of the loss. For example, a patient who has a 60-dB hearing loss would hear in the 30-dB range with use of hearing aids.
Aside from improving hearing, some digital hearing aids also provide noise cancellation, wind noise reduction, wireless capabilities, and an ability to evaluate the environment to determine the best hearing condition for the user.
What Are Types of Hearing Aids?
There are a number of types of hearing aids, and selecting the right one is based on the type and severity of hearing loss, the patient’s listening needs, and their lifestyle. Hearing aids may take an adjustment period of several months to learn the settings and modify them for a particular individual’s hearing needs.
Styles of hearing aids include:
- Behind-the-ear (BTE) aids, in which most parts of the hearing aid are contained in a small plastic case that rests behind the ear. A piece of plastic tubing connects the case to an earmold or an earpiece. This style is easily cleaned and handled, and often used for young children.
- "Mini" BTE (or "on-the-ear") aids are similar to the behind-the-ear (BTE) aids but smaller. They tend to be more comfortable and cause fewer cosmetic concerns.
- In-the-ear (ITE) aids, in which all parts of the hearing aid are contained in a shell that fits in the outer part of the ear. This type is larger than the in-the-canal and completely-in-the-canal aids and may be easier to handle than smaller aids.
- In-the-canal (ITC) aids and completely-in-the-canal (CIC) aids are contained in tiny cases that fit partly or completely into the ear canal. These are the smallest types of hearing aids available but their small size can make them difficult to handle and adjust.
- Bone conduction hearing aids transmit sound directly through the skull to the functioning part of the inner ear involved in hearing (cochleae, for both ears, or cochlea, in the case of single-sided deafness). They may be held against the skull with a steel-spring headband, but this is usually painful and cumbersome. Implantable bone conduction hearing aids have improved sound quality and tolerability for patients.
- Cochlear implants are surgically implanted neuroprosthetic devices that use electrical stimulation to provide hearing
There are also digital and analog hearing aids.
Digital hearing aids convert sound waves into digital signals to produce an exact replication of sound. Computer chips analyze sounds, permitting more complex sound processing to occur, so the performance of the hearing aids in certain situations (for example, reduction of background or wind noise). They can be programmed to meet the needs of specific patterns of hearing loss, and can have many different programs.
Analog hearing aids amplify all sounds in the same manner. Some have a microchip that allows for programmable settings for different listening environments, such as in a quiet place like a library, in a noisy place such as a restaurant, or in a large area like a football field. This type of hearing aid is becoming less common.