Hearing Aid Basics

What’s a hearing aid?

Hearing aids are miniature electronic devices that sit in or on the ear, and selectively amplify and process sounds. All hearing aids contain one or more microphones to pick up sound, an amplifier that amplifies and processes sound, a receiver or speaker that sends the signal from the amplifier into your ear, and a battery, or power source. All these components are packaged into various styles to fit people’s cosmetic needs and power requirements.

Sound processing

Hearing aids today are digital, meaning incoming signals are converted into a series of numbers, which is then processed using mathematical equations. Digital processing enables very complex manipulation of signals, for example, to separate speech from noise. Many hearing aids today have more processing power than your desktop computer – gone are the days when hearing aids were mere amplifiers. Complex algorithms separate sound into different frequency regions and amplify each region selectively, depending on the wearer’s hearing loss. Algorithms also enable different amounts of amplification for soft, moderate, and loud sounds, so sounds are audible, but loud sounds are not uncomfortable or over amplified. And, digital processing ensures a precise replication of the original signal with minimal distortion, resulting in excellent sound quality for even the most discriminating audiophiles. An example of how a digital hearing aid processes sound can be seen below.

Figure 1. Interactive model of how a digital hearing aid processes sound. Courtesy of Unitron Hearing US.

Programmable adjustment

Hearing aids today are programmable, meaning the amplification can be precisely fine tuned and the special features can be adjusted for each wearer, using special hearing aid software on a PC. Hearing aids are customized for both the hearing loss and the preferences of the person who wears them. An example of hearing aid fitting software can be seen below.

Figure 2. Example of software used to customize fit of digital hearing aid. Courtesy of Phonak US.