The Inner Workings
Hearing aids are composed of five elements: a microphone, a speaker, an amplifier, a digital signal processor (DSP) chip and a battery. These parts are enclosed in a hard plastic case made to fit behind-the-ear (BTE) or a custom-made shell that fits in the ear (ITE).
Hearing aids work by collecting sound at the microphone. The microphone converts acoustic sound into an electrical signal, which is sent to the digital signal processor to be digitized. The DSP chip analyzes and processes the signal.
The amplifier boosts the signal and the speaker (receiver) converts it to acoustic sound. Some hearing aid models deliver the sound to the ear with a tube. Other models already have the receiver positioned in the ear canal.
The hearing aid has a compartment to house a battery. A door holds the battery, which swings open to turn the hearing aid off or when the battery needs replacement.
Automatic Noise Processing
Automatic digital noise reduction algorithms can be very effective in reducing the interference of continuous non-speech background noise, such as a computer fan or a car engine. Models equipped with two microphones provide automatic directionality to reduce sound behind you. Combining noise reduction for non-speech noise with twin microphone directionality can improve speech understanding, especially in groups and places with a mixture of background speech and non-speech noise.
Feedback Control
Hearing aids automatically control feedback, which is a whistling or squealing noise. If the signal processor senses feedback it will cancel the sound by generating the same signal milliseconds later so that it is out of phase.
Manual controls
Hearing aids are designed to automatically adjust the volume so that you hear soft, medium, and loud sounds comfortably and clearly. Many hearing aid models also have a button that you can press to adjust the volume yourself. Some models keep track of your volume preferences and learn to make the changes for you.
Some hearing aids have a button or switch that you can use to select programs that are preset by your audiologist. These programs process the sound for music, challenging listening conditions, or specific situations.
Remote controls are available on some hearing aid models, which enable you to adjust both hearing aids simultaneously.
Bluetooth Features
Some hearing aid models have Bluetooth capability for a wireless connection to your cell phone, MP3 player, television or GPS system. With a press of a button, you can activate the Bluetooth feature to send the sound directly to your hearing aids.
