Researchers and clinicians are developing more accurate techniques for selecting and fitting hearing aids for infants and young children.

About Hearing Aids - Hearing Aids and How They Work

A hearing aid is a small, electronic device that amplifies sound. No matter what the size, style or manufacturer, all hearing aids have some of the same basic components: a microphone, an amplifier, a receiver and a battery for power. Many hearing aids also have both internal and external controls.

How a Hearing Aid Works

All parts of the hearing aid work together to amplify sound. The microphone changes sound waves to electrical or, in some instruments digital signals. These signals pass through the amplifier of the aid and are made louder. The amplified electrical signals are changed back into sound waves by the receiver and are channeled into the ear by the earmold or sound bone.

Hearing aids are powered by batteries and feature:

Internal controls that are set by your audiologist. These controls determine which frequencies are amplified (frequency response), the amount of amplification provided by a hearing aid (gain), and the loudest sound the hearing aid can make (saturation response).
External controls that are set by the hearing aid user. They may include:
1. A telecoil switch that allows the hearing aid to be used with a telephone and some assistive listening devices.
2. A volume control, a small that can be adjusted to increase or decrease the loudness of sound. On some hearing aids the volume control is combined with the on/off switch.

Behind-The-Ear (BTE) Hearing Aid

As the name suggests, this type of hearing aid fits behind the ear and is connected to a soft plastic earmold that fits inside the ear. As shown, the ear hook curves around the top of the ear and attaches to a small piece of plastic tubing extending from the earmold.

Sound is routed through the earmold into the ear. The microphone is located at the top of the hearing aid near the ear hook. The battery, amplifier and receiver are all inside the case that fits behind the ear.

Advantages:

Suitable for all ages and for any degree of hearing loss, from mild to profound.
Cosmetically appealing because of small size and placement behind the ear.
Microphone is at ear level, which simulates natural sound reception.
Adaptable to different configurations of hearing loss or to a change in hearing.

Disadvantages:

An earmold that doesn't fit properly or is damaged may cause acoustic feedback (squealing). To prevent this, the earmold may need to be remade periodically to ensure a good acoustic seal in the ear.

In-The-Ear (ITE) Hearing Aid

This type of hearing aid fits completely in the outer ear. The hearing aid case is custom made out of a hard plastic material. As shown, the hearing aid case houses all of the miniaturized hearing aid parts.

Advantages:

Cosmetically appealing due to small size.
Microphone placement simulates natural sound reception.

Disadvantages:

Generally not recommended for children because of the difficulty maintaining a good acoustic seal in an ear that is growing.
For safety reasons, the hard plastic case of this type of hearing aid is not ideally suited for children.
Increased chance of feedback due to closeness of microphone and receiver.
Volume control and battery door may be difficult to use due to small size.
Easily damaged by earwax and/or ear drainage.

In-The-Canal (ITC) Hearing Aid

This type of aid is similar to the in-the-ear hearing aid except that it is smaller and fits mainly in the ear canal. ITC hearing aids are only suitable for milder hearing losses. A completely-in-the-canal (CIC) hearing aid is also available. A CIC aid is smaller yet, fitting entirely in the ear canal. CIC hearing aids may be suitable for mild to moderate hearing losses.

Advantages:

Cosmetically appealing due to small size.
Microphone placement simulates natural sound reception.

Disadvantages:

Seldom recommended for children because of the difficulty maintaining a good acoustic seal in an ear that is growing.
For safety reasons, the hard plastic case of this type of hearing aid is not ideally suited for children.
Increased chance of feedback due to closeness of microphone and receiver.
Volume control and battery door may be difficult to use due to small size.
Easily damaged by earwax and/or ear drainage.
Higher repair rate compared to the other styles.

Bone-Conduction Hearing Aid

Bone conduction hearing aids provide sound through a small vibrator powered by a hearing aid attached to a wearable headband. Used when behind the ear or in the ear aids are not appropriate.

Advantages:

Provides an amplification option for those with essentially conductive hearing loss who have difficulty retaining other hearing aids on their ear.
Microphone placement simulates natural sound reception when an ear-level aid is used with a bone-conduction receiver.

Disadvantages:

Headband is cosmetically less appealing than an ear-level hearing aid alone and may be uncomfortable.

With So Many Hearing Aids, Which One is Right for Me?

There are many considerations when choosing the best style of amplification for a person's needs, including the type, degree and shape of the hearing loss, as well as the manual dexterity and activity level of the person.

Advancing technology has greatly increased the options that are available for the different types of hearing aids. With so many factors involved in the process of selecting amplification, the assistance of an experienced audiologist assures you of choosing a hearing aid that best suits your needs.

Since every hearing loss is different and each person's needs are unique, choosing a hearing aid should be a team effort involving you and a hearing specialist. The Audiology Department at Boys Town National Research Hospital provides a comprehensive approach that will help you make the best decision.

Boys Town National Research Hospital does not endorse specific products or manufacturers. Contact a local certified audiologist or your state's speech and hearing association for services and products available in your area.