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Hearing Aid Technology

Contributed by , director

Hearing aids today are programmable, meaning the amplification can be precisely fine-tuned and the special features can be adjusted for each wearer. The hearing health professional uses special hearing aid software on a computer to fit hearing aids according to an individual’s hearing loss and listening preferences. A range of digital technology and a whole host of features are available in each hearing aid style. Hearing aids can be broadly divided into basic and advanced groups, based on the sophistication of features available in the processor. Even today’s basic digital hearing aids offer way more benefit to individuals with hearing loss than the best hearing aids of previous generations.

Basic hearing aid technology

Even basic digital hearing aids offer more benefit than past generations of hearing aids..
Even basic digital hearing aids offer more benefit
than past generations of hearing aids.

Basic digital hearing aids generally require the wearer to make some manual adjustments in certain listening situations—such as turning a volume control up or down, or pushing a button on the aids in order to reduce noise coming from behind the wearer. The processor may separate incoming signals into two or more channels and process each channel separately. For example, a basic two-channel instrument may be programmed to give more amplification for high-frequency sounds than it gives for low-frequency sounds, in order to accommodate an individual’s hearing loss. Although programmable by computer, basic hearing aids generally have limited adjustments available for fine-tuning to fit unusual patterns of hearing loss. They are also less customizable and automated than hearing aids with advanced technology.

Advanced hearing aid technology

In addition to basic hearing aid technology, each major hearing aid manufacturer offers several levels of advanced digital technology. As the level of technology increases, hearing instruments become more automatic and are equipped with more features to help individuals better communicate in difficult listening situations. For example, instead of utilizing two channels to separate sound for processing, a hearing aid with advanced technology may have eight or more channels. This splits the signal into even smaller frequency bands and therefore offers a higher resolution of signal processing.

Hearing aid features

In the table below, the main features of today’s hearing aids are defined and described. The first seven features, through FM compatibility, may be available to some degree in basic hearing aids as well as advanced hearing aids. Note that this is not an exhaustive list, as hearing aid research is a very active field.

Feature What does it do? How does it help?
Channels Separates the sound signal into discrete sections for processing. Allows the hearing aid prescription to be customized across all pitches. The more channels in the hearing aid, the greater the ability to customize the frequency response.
Directional microphone systems Gives preference to sounds coming from the front of the wearer and reduces sounds coming from other directions. Improves speech understanding in background noise. Satisfaction is higher for hearing aids with directional microphone systems than for hearing aids without them.
Digital noise reduction Determines if the signal contains unwanted noise and reduces the level of noise if present. Makes the background noise less annoying and increases listening comfort. Digital noise reduction has been shown to be effective and preferred by hearing aid wearers.
Impulse noise reduction Smooths quick impulse noises such as car keys rattling, typing on a keyboard and dishes rattling. Improves listening comfort.
Feedback management Reduces or eliminates whistling that can sometimes occur. Improves listening comfort. Basic feedback management systems may reduce the overall amplification in order to remove the whistling. Advanced feedback management systems reduce or eliminate whistling without affecting overall amplification of the hearing aid.
Telecoil Picks up signal from a compatible telephone or other electromagnetically looped system. Improves signal to noise ratio and eliminates feedback because the signal bypasses the microphone and directly enters the processor. Commonly available in public places, like theatres and places of worship.
FM compatibility Enables hearing aids to wirelessly connect with FM systems, sometimes via a special attachment called a boot. Improves signal to noise ratio because the signal bypasses the microphone and directly enters the processor. Commonly used with children in educational settings.
Bluetooth compatibility Enables hearing aids to wirelessly connect to mobile phones, MP3 players and other Bluetooth devices. Improves signal to noise ratio and eliminates feedback or interference because the signal bypasses the microphone and directly enters the processor.
Wind noise reduction Reduces the whooshing noise of wind blowing across the hearing aid microphone(s). Improves listening comfort for people who spend time outdoors—such as golfers, boaters and walkers.
Data logging Stores data about listening environments and user preferences. Data can be viewed by hearing healthcare professional to improve fitting at follow-up.
Learning features Logs settings that are set by the wearer for certain environments and then begins to make these changes automatically. Gradually, the wearer will find that they need to adjust the volume or program less frequently, as the hearing aids become able to make these changes based on the sound environment.
Binaural processing The two hearing aids communicate with each other. This can be used to keep the hearing aids operating synchronously or to stream auditory signals from one aid to the other.

What are the real world benefits of these features?

The real-world benefit of technology is that you can communicate effortlessly.Imagine sitting in a typical busy restaurant, having dinner with friends. Sounds are coming from all directions, such as dishes clanking, people talking and laughing at other tables and waiters rushing about. You’re wearing your new hearing aids and listening to a friend who is sitting across from you at the table. She’s telling a joke.

Your hearing aids are simultaneously reducing impulse noises like silverware clanking onto a plate (impulse noise reduction), reducing the whir of the ventilation system above (digital noise reduction), suppressing the voices of the people at the tables behind you (directional microphone system) and storing information about the listening environment to be saved for later fine-tuning (data logging). They’re doing all of this automatically while amplifying and shaping the speech signal from your friend. You are free to relax and enjoy the punch line.

These are just a few of the possibilities with today’s hearing technology. To learn more about hearing aid technology, contact a hearing professional in your area.

References

  1. Types of hearing aid technology, ASHA, http://www.asha.org/public/hearing/Types-of-Hearing-Aid-Technology
  2. Digital noise reduction: Yes, there is research proving its effectiveness, Hearing Review, http://hearingreview.com/all-news/16215-digital-noise-reduction-yes-there-is-research-supporting-its-effectiveness
  3. MarkeTrak VI: 10-year customer satisfaction trends in the US hearing instrument market, Hearing Review, http://hearingreview.com/products/15604-marketrak-vi-10-year-customer-satisfaction-trends-in-the-us-hearing-instrument-market
  4. It’s sync or stream! The differences between wireless hearing aid features, Hearing Review, http://hearingreview.com/continuing-education/21724-it-s-sync-or-stream-the-differences-between-wireless-hearing-aid-features

This content was last reviewed on: June 5th, 2014

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