The most basic and essential component of any hearing aid is the battery. Without it, the hearing aid won't work. Most hearing aids use zinc-air cells, which are powered by oxygen, but a few use mercury batteries. The size of the hearing aid dictates how long a battery will last. Larger hearing aids have bigger batteries, which can last for about two weeks. Smaller batteries work for three to five days, on average.
In addition to the basic components of the hearing aid, you can add a couple of special features to enhance the quality of sound you're receiving:
A directional microphone allows you to hear sounds directly in front of you more clearly than sounds behind you and to the sides, so that you can focus on conversations without worrying about annoying background noise. You can switch between a directional microphone and regular microphone, depending on your listening situation. Directional microphones will fit only on the larger hearing aids.
A telecoil allows you to switch from your normal hearing aid microphone to the "T" setting in order to filter out environmental sounds when you're on the phone. Telecoils work only with hearing-aid-compatible phones. (All wired phones manufactured today must be hearing-aid-compatible, but many cordless and cell phones aren't compatible.) Many theaters, places of worship and auditoriums have induction-loop systems, which will also work with your hearing aid's "T" setting.
Telecoils aren't the only devices that can help people with hearing loss use the phone. Amplified phones have a louder ringer, as well as flashing lights, to signal incoming calls. Text phones transcribe the call into text for people who are severely hearing impaired. A loopset has a wire loop that goes around the neck and connects to a mobile phone. The loop sends sound from the phone to the hearing aid and filters out background noise.
If you find that you still have to turn the TV volume way up to hear it, you might benefit from direct audio input. Many hearing aids can be plugged directly into the television, computer, CD player, and radio for clearer sound.
Research to Improve Hearing Aids
Hearing aids available today are smaller and more powerful than ever, and researchers are aiming for even higher sound quality in the future. They're looking for ways to better amplify the sound signal and reduce feedback using the latest computer technology.
One avenue of research is focusing on a very unusual subject -- the fly Ormia ochracea. This tiny fly has very precise hearing, which allows it to determine the source of a sound with uncanny ease. Scientists are modeling directional microphones after the fly's ears. The new microphones will help amplify sounds from certain directions, while suppressing sounds from other directions to help people focus on conversations when they are surrounded by background noise.