What are hearing aids?
Hearing aids are sound-amplifying devices designed to aid people who have a hearing impairment.
Most hearing aids share several similar electronic components, including a microphone that picks up sound; amplifier circuitry that makes the sound louder; a miniature loudspeaker (receiver) that delivers the amplified sound into the ear canal; and batteries that power the electronic parts.
Hearing aids differ by:
- technology used to achieve amplification (i.e., analog vs. digital)
- special features
Some hearing aids also have earmolds or earpieces to direct the flow of sound into the ear and enhance sound quality. The selection of hearing aids is based on the type and severity of hearing loss, listening needs, and lifestyle.
What are the different styles of hearing aids?
Behind-the-ear (BTE) aids: Most parts are contained in a small plastic case that rests behind the ear; the case is connected to an earmold or an earpiece by a piece of clear tubing. This style is often chosen for young children because it can accommodate various earmold types, which need to be replaced as the child grows. Also, the BTE aids are easy to be cleaned and handled, and are relatively sturdy.
“Mini” BTE (or “on-the-ear”) aids: A new type of BTE aid called the mini BTE (or “on-the-ear”) aid. It also fits behind/on the ear, but is smaller. A very thin, almost invisible tube is used to connect the aid to the ear canal. Mini BTEs may have a comfortable ear piece for insertion (“open fit”), but may also use a traditional earmold. Mini BTEs allow not only reduced occlusion or “plugged up” sensations in the ear canal, but also increase comfort, reduce feedback and address cosmetic concerns for many users.
In-the-ear (ITE) aids: All parts of the hearing aid are contained in a shell that fills in the outer part of the ear. The ITE aids are larger than the in-the-canal and completely-in-the-canal aids (see below), and for some people may be easier to handle than smaller aids.
In-the-canal (ITC) aids and completely-in-the-canal (CIC) aids: These hearing aids are contained in tiny cases that fit partly or completely into the ear canal. They are the smallest hearing aids available and offer cosmetic and some listening advantages. However, their small size may make them difficult to handle and adjust for some people.
What is the difference between analog and digital hearing aids?
Analog hearing aids make continuous sound waves louder. These hearing aids essentially amplify all sounds (e.g., speech and noise) in the same way. Some analog hearing aids are programmable. They have a microchip which allows the aid to have settings programmed for different listening environments, such as in a quiet place, like at a library, or in a noisy place like in a restaurant, or in a large area like a soccer field. The analog programmable hearing aids can store multiple programs for the various environments.
As the listening environment changes, hearing aid settings may be changed by pushing a button on the hearing aid. Analog hearing aids are becoming less and less common.
Digital hearing aids have all the features of analog programmable aids, but they convert sound waves into digital signals and produce an exact duplication of sound. Computer chips in digital hearing aids analyze speech and other environmental sounds. The digital hearing aids allow for more complex processing of sound during the amplification process which may improve their performance in certain situations (for example, background noise and whistle reduction). They also have greater flexibility in hearing aid programming so that the sound they transmit can be matched to the needs for a specific pattern of hearing loss. Digital hearing aids also provide multiple program memories. Most individuals who seek hearing help are offered a choice of only digital technology these days.
What are some features for hearing aids?
Hearing aids have optional features that can be built in to assist in different communication situations. For example:
- Directional microphone may help you converse in noisy environments. Specifically, it allows sound coming from a specific direction to be amplified to a greater level compared to sound from other directions. When the directional microphone is activated, sound coming from in front of you (as during a face-to-face conversation) is amplified to a greater level than sound from behind you.
- T-coil (Telephone switch) allows you to switch from the normal microphone setting to a “T-coil” setting in order to hear better on the telephone. All wired telephones produced today must be hearing aid compatible. In the “T-coil” setting, environmental sounds are eliminated, and sound is picked up from the telephone. This also turns off the microphone on your hearing aid so you can talk without your hearing aid “whistling.”
The T-coil works well in theaters, auditoriums, houses of worship, and other places that have an induction loop or FM installation. The voice of the speaker, who can be some distance away, is amplified significantly more than any background noise. Some hearing aids have a combination “M” (Microphone) / “T” (Telephone) switch so that, while listening with an induction loop, you can still hear nearby conversation.
- Direct audio input allows you to plug in a remote microphone or an FM assistive listening system, connect directly to a TV, or connect to other devices such as your computer, a CD player, tape player, radio, etc.
- Feedback suppression helps suppress squeals when a hearing aid gets too close to the phone or has a loose-fitting ear mold.
The more complicated features may allow the hearing aids to best meet your particular pattern of hearing loss. They may improve their performance in specific listening situations; however, these sophisticated electronics may significantly add to the cost of the hearing aid as well.