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Every new year holds fresh promise - the promise of new growth and development. It is a time for getting back to basics and reducing the clutter in our lives. Just as new snow blankets the ground, it is a time for wiping the slate clean and starting the year with a fresh outlook.
In this way, hearing aid terminology can be simplified to create a cleaner slate upon which to build in the new year. Anticipating that the year will bring innumerous technological advances, it's refreshing to review the fundamentals of hearing aid features and their benefits. Current hearing aid feature descriptions are littered with words like "spectral," "adaptive," and basically every phrase that can be built around the words "speech" and "noise." In all of these labels, the true meaning and functionality of the feature often become murky and muddled. At times it is difficult to determine from the feature name or even its description what exactly it is doing and whether it falls into the category of "noise reduction," "expansion," or another aspect of hearing aid processing.
Add to this already overcrowded landscape of current hearing aid marketing terminology the new features and feature enhancements that will launch in the year to come, and it is easy to become overwhelmed. Like its recent predecessors, 2012 promises to be a year filled with greater use of wireless binaural processing and improved automatic functionality of hearing aid features. In short, hearing aids will get faster and better at signal processing, and the hearing aid market will be awash in new terminology to label and brand these advances.
With the goals of de-cluttering and simplification in mind, below is a list of features defined in generic terms with their core functionality:
Directionality: The only method to increase the signal-to-noise ratio and have a direct effect on speech intelligibility in noise, directionality attenuates sounds - typically noise - from the rear and/or sides of the listener.
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Omnidirectional processing does not attenuate sounds from any direction around the listener.
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Automatic-switching directionality can change between a directional and omnidirectional response based on the listening environment detected.
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Adaptive directionality typically selects the appropriate direction and/or width of the directional beam, often times based on the listening environment.
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Asymmetric directionality provides one ear with a directional response and the other ear with an omnidirectional response.
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Bass boost or low-frequency equalization increases the gain in the low frequencies in the directional program to overcome the inherent low-frequency gain roll-off in directional processing.
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Band split directionality also works to overcome the low-frequency gain attenuation of directional processing by applying omnidirectional processing in the low frequencies and directional processing in the high frequencies.
Noise reduction: Noise reduction is largely a comfort feature that makes listening in noise less difficult by detecting noise-like input sounds and reducing gains in the affected channels.
- Wind noise reduction focuses on eliminating wind noise as compared to ambient or environmental noise.
Compression: At input levels greater than a given kneepoint, compression provides the greatest amount of gain to lower-intensity input sounds and the smallest amount of gain to higher-intensity input sounds.
Expansion: Expansion is the opposite of compression and assigns the least amount of gain to low-level sounds beneath its kneepoint to increase listening comfort.
Feedback management: This feature reduces or eliminates feedback spikes in the output signal through phase cancellation techniques or by reducing or limiting gain.
Environmental steering: Environmental steering uses acoustic cues to classify and optimize hearing aid characteristics and settings for the listening environment detected.
Frequency lowering: This feature makes high-frequency sounds more audible to the listener by super-imposing inaudible high frequencies to a lower frequency range (in frequency transposition) or by compressing the entire frequency spectrum into the range of the patient's hearing attainable by hearing aid amplification (in frequency compression).
Binaural wireless processing: This feature can optimize hearing aid settings to the environment for better binaural listening and can automatically relay user changes (like the program setting) from one hearing aid to the other through wireless technology.
Although the above features do not constitute an exhaustive list, they nevertheless create a basic framework used by most hearing aids on the market today. These generic "bins" of hearing aid features might be used to categorize new advances and their benefits. No one knows exactly what the future will bring, but remembering where we've come from often helps us understand where we're going.
It's a new year! So take a deep breath, and enjoy the ride of hearing aid technology advances in 2012.
Tammara Stender, AuD, is a senior audiologist with GN ReSound in Chicago. She plans and conducts clinical trials for newly developed hearing aid technology and prepares documentation for released products. Her research interests include hearing aid benefit and satisfaction, the occlusion effect, and spatial localization abilities with hearing aids. She is a fellow of the American Academy of Audiology, a certified member of the American Speech-Language-Hearing Association, and a member of the Illinois Academy of Audiology. In addition to her research work, Dr. Stender is a clinical preceptor for AuD students at Rush and Northwestern universities in Chicago and Northeastern University in Boston. For more information, visit www.gnresound.com.
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