What Is Hearing Aid Compression and Expansion?


Picture of sound waves.

The primary purpose of a hearing aid is to enhance audibility and make speech sounds more natural to hear, all while maintaining loudness tolerance. The different technologies behind hearing aids have constantly been improving.

Unlike the hearing aids of the past, the hearing aids that are available now rely on a range of features that are customized to address your unique hearing needs. Two elements of which you should be aware are hearing aid compression and hearing aid expansion.

What Is Wide-Dynamic Range Compression?

Wide-dynamic-range compression, or WDRC, technology is able to improve the hearing of people who have a severe form of hearing loss. Instead of merely making sounds louder, hearing aid compression works by manipulating sound. It allows people who wear hearing aids to hear sounds that they were unaware that they were not hearing.

Why Would I Want Hearing Aid Compression?

Your dynamic range is the difference in volume between the loudest sound you are able to tolerate and softest sound you can hear, such as the difference between a shout and whisper. If you have hearing loss, you will have a limited dynamic range as the softest sound you can hear is much louder than that of someone who has unimpaired hearing. Hearing aids that use WDRC make sounds louder at varying levels that depend on how loud the sounds initially were. The hearing aids can detect higher frequency sounds and then convert or compress them to lower frequency sounds that you are able to hear. While the nature or characteristics of the sound are modified, you are still able to hear what you were unable to hear before.

With hearing aid compression, you can hear all sounds while being able to distinguish between a shout and a whisper.

What Is Hearing Aid Expansion?

Many of the hearing aids that are in use today also use expansion technology, which is intended to reduce the audibility of extremely soft sounds. By reducing low-level noise, expansion can prevent the sounds, such as circuit noise made by your hearing aid or background noise, that can interfere with how well you are able to hear the sounds on which you truly want to focus.

However, one concern about the expansion technology in hearing aids is whether it can affect how well you are able to hear or recognize speech, particularly with regard to the recognition of consonant sounds.

If you have hearing loss, the compression or expansion technology used in hearing aids may help to enhance your hearing by making it easier for you hear sounds in a certain way or by dimming noises that can impair how well you can hear desired sounds. A licensed hearing health professional can advise you of the type of hearing loss you may be experiencing and what type hearing aid technology would be most beneficial to you.

Page medically reviewed by Kevin St. Clergy, Audiologist, on April 29, 2020.

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