Parts of a Hearing Aid
Today's hearing aids are so tiny, It's hard to believe they contain five distinct parts: a microphone, digital processor/amplifier, receiver, volume control and battery. Let's see how these components work together to bring more natural hearing to hearing aid wearers.
Hearing Aid Microphone
Hearing aids process sound so people with hearing loss can more easily understand it. Sound may be amplified for example, or separated into different parts, like background noise and speech. It all begins with the hearing aid microphone. The microphone's function is to convert the sound waves we hear into electricity, so they can be digitized, and then enhanced for the needs of people with hearing loss.
Hearing Aid Digital Processor/Amplifier
The processor takes the electrical signals sent from the microphone, and changes them into digital signals (using 0s and 1s). This is called analog-to-digital conversion (A-to-D). Once in digital format, sound is more easily perfected in ways patients require. Enhancements to the original sound, such as frequency amplification, noise and wind reduction, and feedback cancellation, happen at this stage. The modifications applied depend on each hearing aid wearer's degree of hearing loss and their lifestyle requirements.
Once the processing has occurred in a digital format, the signal is converted back to an analog signal, (D-to-A) which readies it for its next stop: the hearing aid receiver. These are complex procedures happening incredibly fast.
Hearing Aid Receiver
Now, the hearing aid must change enhanced signals back into sound waves so the brain can properly perceive them. Enter the hearing aid receiver. Its job is to convert electrical signals into acoustical output signals, or sound waves, and direct them into the wearer's ear canal for the brain to hear.
Receivers look similar to microphones. Some hearing aid designs place the receiver right in the ear canal. Some styles use a tiny tube to connect the receiver to an ear mold worn in the ear canal. Other hearing aid models house the receiver in a shell that hides behind the ear.
Hearing Aid Volume Control
As its name implies, the volume control adjusts the loudness setting in a hearing aid. Most modern models adjust the volume automatically as the wearer moves from one listening environment to another. Some hearing aid users prefer to have a manual volume control such as a dial or a switch in order to manage volume themselves.
Hearing Aid Battery
The battery supplies the power to turn the electronic components on and off. The batteries most commonly used for hearing aids use zinc and oxygen components, and are known as “zinc-air” batteries. The sticky tabs on zinc-air batteries prevent air from coming into contact with the zinc electrodes. The battery will not operate until the tab is removed. Depending on the complexity of the hearing aid functions, battery life runs approximately 3 days to 2 weeks.
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