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There are many types of hearing aids, which vary in size, power and circuitry. Among the different sizes and models are:
Body worn aids
This was the first type of hearing aid, and thanks to developments in technology they are now rarely used. These aids consist of a case containing the components of amplification and an ear mold connected to the case by a cord. The case is about the size of a pack of cards and is worn in the pocket or on a belt. Because of their large size, body worn aids are capable of large amounts of amplification and were once used for profound hearing losses. Today, they have largely been replaced by BTEs
Behind the ear aids (BTE)
BTE aids have a small plastic case that fits behind the ear and conducts sound to the ear canal, usually through an earmold that is custom made. BTEs can be used for mild to profound hearing losses and are especially useful for children because of their durability and ability to connect to assistive listening devices such as classroom FM systems. Their colors range from very inconspicuous skin tones for adults to bright colors and optional decorations for children. Recent innovations in BTEs include miniature "invisible" BTEs with thin hair-like sound tubes (see open-fit devices below). These are often less visible than ITEs and some keep the ear canal more open so listeners may still utilise their residual natural hearing (most helpful for those with normal hearing in the lower frequencies). Ideal for high frequency losses, these miniature versions are generally used for mild to moderate hearing loss.
In the ear aids (ITE)
These devices fit in the outer ear bowl (called the concha); they are sometimes visible when standing face to face with someone. ITE hearing aids are custom made to fit each individual's ear. They can be used in mild to some severe hearing losses. Feedback, a squealing/whistling caused by sound leaking out of the aid and being amplified again, may be a problem for severe hearing losses. Some modern circuits are able to provide feedback regulation or cancellation to assist with this. Traditionally, ITEs have not been recommended for young children because their fit could not be as easily modified as the earmold for a BTE, and thus the aid had to be replaced frequently as the child grew. However, there are new ITEs made from a silicone type material that mitigate the need for costly replacements. Moreover, ITEs are much easier than floppy BTEs to keep on a small child.
In the canal (ITC), mini canal (MIC) and completely in the canal aids (CIC)
ITC aids are smaller, filling only the bottom half of the external ear. You usually cannot see very much of this hearing aid when you are face to face with someone. MIC and CIC aids are even smaller and often not visible unless you look directly into the wearer's ear. These aids can be used for mild to moderately-severe losses. CICs are usually not recommended if you have good low frequency hearing as the "plugged up effect" may make your voice resonate (the "occlusion effect").
For diagrams and pictures of these different types, see this external website.
Open-fit devices
Recently a new device has come on the market, the "Open-fit" or "Over-the-Ear" OTE Hearing Aid. Usually quite discrete, these are small Behind-the-ear type devices, with a much finer clear tube that runs down into the ear canal. Inside the ear canal, there is a small soft silicone dome or a molded, highly vented acrylic tip that holds the tube in place. There are also devices available which have an external speaker, placed inside the ear canal, and connected to the hearing system itself by a thin cable. The external speaker allows the device behind the ear to be even smaller. These devices are designed to reduce the "occlusion effect", which is the amplification of your own voice when your ears are plugged up (try sticking your fingers in your ears and talking). Conversely they increase the possibility of feedback, and as such are limited to moderate high frequency losses. Open-fit devices are very beneficial for High-Frequency hearing losses, and have been introduced by all major hearing aid companies.
Bone Anchored Hearing Aids (BAHA)
The BAHA is a surgically implanted system that uses bone transmission as a pathway for sound to travel to the inner ear, bypassing the external auditory canal and middle ear. A titanium "post" is surgically embedded into the skull with a small abutment exposed outside the skin. A sound processor sits on this abutment and transmits sound vibrations to the external abutment of the titanium implant. The implant vibrates the skull and inner ear, which stimulate the nerve fibers of the inner ear, allowing hearing. Bone anchored hearing aids are however some of the most expensive of any kind of aid.
Eyeglass aids
During the late 1950s through 1970s, before in-the-ear aids became common (and in an era when thick-rimmed eyeglasses were popular), people who wore both spectacles and hearing aids frequently chose a type of hearing aid that was built into the temple pieces of the spectacles. However, the combination of glasses and hearing aids was inflexible: the range of frame styles was limited, and the user had to wear both hearing aids and glasses at once or wear neither. Today, most people who use both glasses and hearing aids simply use in-the-ear types. There still are some specialized situations where hearing aids built into the frame of eyeglasses can be useful, such as when a person has hearing loss mainly in one ear: sound from a microphone on the "bad" side can be sent through the frame to the side with better hearing.
* This can also be achieved by using CROS or bi-CROS style hearing aids, which are now wireless in sending sound from the "bad" or "worse" side to the better side. These types of hearing aids are much more frequently used than any eyeglass style.
Recently, a new type of eyeglass aid has been introduced by the Dutch company Varibel. These 'hearing glasses' feature directional sensitivity: four microphones on each side of the frame effectively work as two directional microphones, which are able to discern between sound coming from the front and sound coming from the sides or back of the user. This allows for amplification of the sound coming from the front, the direction in which the user is looking, and suppression of sound coming from the sides or back. Only very recently has the technology required become small enough, in size, to be put in the frame of the glasses. As a recent addition to the market, the geographical market for this particular hearing aid is currently limited to a few European countries.
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Important notice:
The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other
qualified health provider with any questions you may have regarding a medical condition.
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