Types of Hearing Aids
There are several types of hearing aids – behind the ear, in the ear, in the canal and implantable hearing aids.
Behind-the-Ear (BTE) Hearing Aids
This slim hearing aid fits on top of and tucked behind the ear. Typically, an ear mold [see below] is used to both anchor the hearing aid to the ear and to direct amplified sound into the ear canal, so a tight fit is required for them to do their job properly.
BTE hearing aids are suitable for almost all types and degrees of hearing loss, and for persons of all ages. Mini BTE hearing aids, rather than full size, are the most appropriate style for infants and young children. As babies grow, they will need their ear molds replaced frequently. The new ear mold is attached to the existing hearing aid, so the entire aid does not need to be replaced. BTE hearing aids come in different colors and older children may enjoy selecting colors or stickers to express their individual styles and personalities. Ear molds also come in a wide range of colors.
BTE hearing aids are easy for parents to “check on” as they can be seen from behind the child and can also be “fixed” to stay in the ear or, at least on the child, and prevent loss. This can be done by using toupee tape, or using other attachments that secure the hearing aid to the child’s ear or clothing. Ask your audiologist for suggestions to use with your child’s hearing aids.
In-the-Ear (ITE) Hearing Aids
ITE hearing aids are built into a custom-made shell obtained from an impression of the outer ear and ear canal. They are appropriate for adults with mild to moderately severe hearing loss. ITE aids are very small and must be replaced as the ear grows and, so they are not used with infants or young children. Their small size and hard outer shell make them unsafe for babies and young children.
It is not unusual for older children to ask their parents for an ITE aid as they approach middle or high school. ITE aids can be a viable option for the child who has worn a BTE-style aid previously; however, it is recommended that the child’s outer ear has slowed in growth and that parents be certain that the aids is a good fit for the child’s degree and type of hearing loss. Learning that an ITE hearing aid is not an option can be very disappointing and discouraging to an older child. It is recommended that the parent consider speaking to the child’s audiologist prior to the appointment if the child and family are considering this kind of change. The audiologist can help guide the parents in discussions with the child as well as prepare the child, the parent and the audiologist for an upcoming appointment in which new hearing aids are going to the topic of discussion.
In-the-Canal (ITC) Hearing Aids
ITC aids fit into the ear canal and are customized to fit the size and shape of the user's ear canal. ITC aids are smaller than ITEs and must be replaced as the ear grows and, as a result, are not often selected for pediatric use. Like the in-the-ear aid, this style is recommended most frequently for mild to moderately severe hearing loss. ITC aids are the most popular style with adults. ITC aids, like the in-the-ear aids, may be a viable option for a child after his ear growth has slowed provided that the child’s type and degree of hearing loss can be accommodated by an aid this size.
Completely-in-the-Canal (CIC) Hearing Aids
CIC aids are built into a custom-made shell obtained from an impression of the ear canal. The CIC, however, fits a bit farther into the ear canal and extends deeper toward the eardrum than the in-the-canal hearing aid. Although generally not "invisible," this hearing aid style is often the least conspicuous or noticeable. These instruments are usually appropriate for mild to moderate, and for sloping high-frequency hearing losses. Like in-the-ear and in-the-canal hearing aids, they are not appropriate for infants or young children.
Implantable Hearing Aids (IHAs)
IHAs are comprised of both bone-anchored hearing aids, commonly known as a BAHA, and middle ear implants (MEIs). A bone anchored device is useful for people with either congenital atresia of the ear canal or chronic middle ear dysfunction, which prevents the optimal use of conventional hearing aids. Many candidates for bone anchored hearing aids have successfully used bone conductors which gently oscillate, or vibrate, the skull and reproduce sound waves that activate the users’ hearing mechanisms.
The U.S. Food and Drug Administration (FDA) has approved the use of BAHAs for all age groups, including children as young as 2 years old. The long-term experience with use of the BAHA in Sweden and England and its increasing popularity in North America suggests that the device may be a preferred alternative to surgery to open the ear canal or repair the middle ear mechanism, particularly in children with the Treacher-Collins or Goldenhaar syndrome.
Ear molds are created from an impression of the outer ear and ear canal, and are custom-made to fit the ear and keep hearing aids in place. It takes about 10 minutes to make an impression of the ear out of a special material. The impression is taken in the audiologist’s office and sent to an ear mold manufacturer for production. Ear molds can be “rushed” through the process for an additional fee; however, it generally takes 10-14 days from the time the ear impression is taken until the new ear mold arrives back at the audiologist’s office.
Ear molds, unlike hearing aids, need to be replaced fairly often in children. New ear impressions need to be taken about every time a child’s shoe size changes because the outer ear grows at about the same rate as the foot. This means that ear molds are replaced most often for infants and toddlers. By the time a child is 6 years old, the need to replace ear molds on a regular basis will decrease significantly.
When the ear mold isn't fitting well, amplified sound will escape the ear canal and be amplified again by the hearing aid microphone, producing “acoustic feedback” in the form of a high-pitched squealing sound. Note that a lack of “acoustic feedback” does not necessarily mean that the ear mold is still fitting optimally; however, presence of a consistent or intermittent squeal when the hearing aid microphone is unobstructed is almost always a sign that it’s time to check the child’s ear mold fit.
Ear molds come in a variety of materials, but are generally either made of a “soft” or “hard” material. An audiologist selects the ear mold material for a given client based on a number of factors, primarily the type and degree of the hearing loss. It is generally recommended that young children wear ear molds made of “soft” material. Soft material is flexible and protects the child from being injured by the ear mold should the child bump his or her ear during sports or rough play. Ear molds come in a wide range of colors.