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 the same basic components: a microphone, an amplifier, a receiver and a battery for power. Most hearing aids also have internal and external controls. There are so many types and manufacturers that it can be difficult to understand easily what is being offered.  Ask your audiologist to explain each feature and how it may benefit you.

How a Hearing Aid Works
  All parts of the hearing aid work together to amplify sound. The microphone changes sound waves to electrical 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 ear mold or sound bone. The amount of amplification provided by a hearing aid is called "gain".

Behind-The-Ear (BTE) Hearing Aid
  This type of hearing aid fits behind the ear and is connected to a soft plastic ear mold which fits inside the ear. The ear hook curves around the top of the ear and attaches to a small piece of plastic tubing extending from the ear mold. Sound is routed through the ear mold 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 ear mold that doesn't fit properly or is damaged may cause acoustic feedback (squealing). To prevent this, the ear mold 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. 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 or Completely in the Canal (CIC)
  This type of hearing aid fits down into the ear canal, or completely in the ear canal. The hearing aid case is custom made out of a hard plastic material. 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:
    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. CIC does not have a volume control wheel, most of the time. Easily damaged by earwax and/or ear drainage. Higher repair rate compared to the other styles.

Body-Style Hearing Aid
  This style of hearing aid may be worn in a harness on the chest. The microphone is located either on the top, front, or side of the aid. A cord connects the aid to a receiver which is attached to an ear mold.

• Advantages:
    Can be used by people needing powerful amplification, particularly when a good acoustic seal is needed and where feedback is a problem. Can be used by people who have difficulty keeping a hearing aid on the ear or who have difficulty using the small controls of an ear-level aid because of reduced dexterity.

• Disadvantages:
    Microphone is not at ear level and doesn't provide natural sound reception at the ear. If worn under clothing, noise can result from clothes rubbing against the microphone. If a body aid is worn on the chest, microphone and controls can be damaged by food or liquid spills. Cosmetically less appealing and cumbersome due to large size and cords.

Bone-Conduction Hearing Aid
  This type of aid is similar to the other hearing aid except a head band clamps the hearing aid tightly to the skull bone behind the ear.  There is also a new option, called a Bone Anchored Hearing Aid *BAHA, that is surgically implanted into the skull and has a prosthetic attachment.

• 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:
    If the bone-conduction receiver is worn with a body-style hearing aid, the disadvantages listed under body-style hearing aid will apply. Headband is cosmetically less appealing than an ear-level hearing aid alone and may be uncomfortable.