American Medical Association Family Medical Guide - American Medical Association [716]
Hearing aids
Hearing aids are battery-powered devices that fit in the ear to electronically increase the volume of sound. Hearing aids contain a tiny microphone that transforms sounds into electrical signals, an amplifier that increases the strength of the signals, and a speaker that turns the signals into louder sounds. Some hearing aids are equipped with a device called a telecoil (also called a T-coil or T-switch), which converts electromagnetic fields into sound.
Hearing aids come in a variety of styles. Analog hearing aids are programmable or adjustable. Digital hearing aids are programmable and can be made to filter out some of the background noise and feedback that can occur with some analog hearing aids. Disposable hearing aids are available for people who have mild to moderate hearing loss.
It is important to choose both the right kind of hearing aid and one that fits properly. If you need a hearing aid, your doctor will refer you to an audiologist or a hearing aid dealer for an evaluation and fitting for a hearing aid. Tell your doctor or ear specialist immediately if you notice any deterioration in your hearing between regular checkups or after you get a hearing aid.
Behind-the-ear aid
A behind-the-ear aid contains a microphone, amplifier, and battery in a small, lightweight, plastic case worn behind the ear. The earphone, which is connected to the rest of the device by a short tube, fits into the outer ear and seals it to prevent amplified sound from being lost. People with varying degrees of hearing loss can benefit from behind-the-ear aids.
In-the-ear aid
An in-the-ear aid consists of a microphone, amplifier, and battery housed in a lightweight plastic case worn inside the ear. The aid is molded to seal the ear canal to prevent amplified sound from being lost. These aids are less awkward to put in the ear than behind-the-ear aids, and the volume is easy to adjust. In-the-ear hearing aids are usually not recommended for children because the case has to be replaced as the child grows.
In-the-canal and completely-in-the-canal aids
In-the-canal aids, which remain only slightly visible when inside the ear, and completely-in-the-canal aids, which cannot be seen at all, are customized to fit inside the ear canal. People whose hearing loss ranges from mild to moderately severe can benefit from in-the-canal and completely-in-the-canal aids. These aids are not recommended for everyone, however, including children who are still growing. Some people may have difficulty inserting, removing, or adjusting in-the-canal aids, and excessive earwax or drainage from the ears can damage them.
Hearing aids
Implantable bone conduction hearing device
Some people—such as those whose ear canal has been narrowed by disease or surgery or who were born with a small ear canal that causes hearing problems—may not be able to wear a standard hearing aid. People who have chronic ear drainage or who are allergic to the plastic used in hearing aids may not be able to wear a standard hearing aid. For these people, an implantable bone conduction hearing device may be used to help improve hearing.
To implant a bone conduction hearing device, a surgeon makes an incision in the scalp behind the ear, drills a hole in the outer part of the skull, and screws a small device that contains a magnet in the hole. The person wears a microphone that converts sound waves into electrical impulses that stimulate the magnet, making it vibrate. The brain perceives the vibrations as sounds.
Cochlear implants
Some children are born with total sensorineural hearing loss, or nerve deafness, and some children and adults develop the disorder as a result of damage to the inner ear. To help a person with severe sensorineural hearing loss understand speech better, a tiny electronic device called a cochlear implant can be surgically implanted in the inner ear. Cochlear implants produce sound by stimulating undamaged nerves in the inner ear, not by amplifying sound as a hearing aid does. Cochlear implants do not restore normal hearing—they help a person