The hearing aid is a fairly simple piece of technology that helps individuals who suffer from varying degrees of hearing loss. It acts in much the same way as the ear itself, and has parts that serve some of the same functions as parts of the natural ear. Hearing aid parts include amplifiers to increase the volume to make sounds audible for the individual, while speakers and receivers turn these sounds into a form that the ear and brain can understand.
A hearing aid is an electronic device, so it requires some kind of power source. Most have some type of tiny battery inside. Many have batteries similar to those found in watches or other small devices. As the life of these hearing aid parts varies among models, the individual type will dictate whether batteries have to be changed every few days or if they will last for a few weeks.
As the hearing aid acts in a way similar to the human ear, it needs a way to receive sounds from the environment. This is usually in the form of a small microphone. The number of microphones also varies among different types of hearing aids, and can be adjusted to pick up sounds of different frequencies or from different areas around the person.
Much like the mechanics of the middle ear, some hearing aid parts act to amplify sounds received in the ear. These parts are generally in the form of amplifiers that increase the strength of the sound they receive. Amplifiers do this by taking the sounds as an electrical signal and raising the quality and volume of that signal. This amplifier is generally attached to some kind of receiver, which then gets the magnified signal.
Once the increased sound is processed by the amplifier, it is sent to the next of the hearing aid parts. Either a speaker or a receiver is attached to the amplifier, and is responsible for changing the signal back into a form that the individual's ear can hear and brain can understand. The hearing aid still requires help from the individual's own ear to complete the process, as the sound magnified by the different hearing aid parts is then sent to the brain via the natural parts of the ear.
There are often a number of other electrical hearing aid parts as well, although these vary among models. Switches allow the individual to turn the hearing aid on and off to save battery power while it isn't in use. Many also have a volume control, allowing the same hearing aid to be used in a number of different situations. Some also have an adapter that makes phone conversations easier to manage.