When too much sound is presented to those hearing aid systems, or ears for that matter, that lack an adequate input range, they simply distort all of the sounds passing through them. Anytime this happens the person on the receiving end is left with nothing but distorted, sound garbage for output.
The point of critical importance in hearing aid circuitry surrounds their microphones, and the analog to digital converters that are located on the input side of every modern hearing aid system.
The problem is that our natural, normal hearing’s operational range is simply incredible.
Even today acoustic, and electrical engineers have a great deal of trouble even coming close to matching it, especially in something as small as a hearing aid, which is to be worn on, or even deeply within the ear. When healthy, our human ears can detect an incredibly small disturbance in the air pressure waves striking the eardrum.
From an engineer's standpoint this represents being able to detect sounds that on one end have but, .002 dynes per centimeter squared present at the eardrum. (I had to put that in for my engineering patients, and their buds.) The point is, that this is a truly tiny disturbance in the air. Yet, the healthy human ear can still detect it.
While on the upper end of our own operational system, we reach saturation levels (experienced by us as pain, or discomfort) at a point representing over one hundred million times more energy being present at that same eardrum, that just moments before was hearing that pin drop from across the room.
We created the decibel scale just to cope with this incredibly wide range of acoustic energies that we deal with everyday. Just remember that this is a logarithmic, rather than a linear scale, with energies on the upper end, hundreds of million times greater than at their zero point. In fact, if things weren’t confusing enough, we created two such scales, one that measures human hearing threshold levels, known as the HTL scale, and the other, or absolute, or sound pressure level scale used whenever we are talking about any equipment’s output, known as the SPL scale.
The reason for these two different decibel scales is very simply that we can’t hear nothing.
The zero point on our absolute, or SPL scale represents no sound, or a complete absence of vibrational energies being detectable. Yet audiology wanted a means to easily understand, and explain the range of human hearing, which obviously starts somewhere above that zero point on the SPL, or absolute sound pressure level scale.
So, in order to establish this range of human hearing that we see everyday, on every audiogram describing someone’s hearing thresholds, the V. A. conducted a very wide ranging study of eighteen to twenty-one year old college students just after world war two.
They needed to establish just what “normal hearing” was, in order to fairly deal with the millions of returning veterans suffering from hearing loss due to the noise exposures associated with war.
From that first mega-study of human hearing we developed the second scale, that we know as the HTL, scale, which deviates approximately twenty decibels from the SPL scale. (From a practical standpoint we simply add twenty decibels across the board, but this is actually an average at each of the frequencies tested, and some are greater, some less, but they average twenty so that’s what we use in practice.)
Now, just what does this have to do with hearing aids that don’t function well in noise?
Remember that microphone and analog to digital converter I talked about above, well the problem is that many of today’s systems operate well when things are quiet, or even moderately noisy. However, many of these same systems lack the upper end operational range, and headroom to handle those really noisy, fun social situations.
When any hearing aid system lacking the range gets too much noise, like at that anniversary, or birthday party being held at your favorite restaurant, what happens is that they saturate. As the term implies a saturated circuit simply can’t handle any more. Very simply, any time any system is being saturated, it’s output cannot be anything but distorted.
No matter how fast, powerful, or awesome the processor chip behind that saturated input circuit, if you put garbage into it, in the form of a corrupted signal, you can’t help but get a corrupted signal, garbage out.
Engineers put it very simply; garbage in, garbage out.
It is the very reason that range matter in hearing aids. The more active the lifestyle, the more it matters. As it is in those active full lifestyles that we find ourselves in the greatest range of sound environments.
Folks sitting quietly around their TVs, who rarely venture beyond might not notice. But, anyone experiencing the full range of life’s acoustic treasures surely will.
That is why range, and headroom matters. Life is full of all sorts of sounds, some incredibly soft, others rockingly loud. Some of the sounds life serves up are real loud, but no matter what, or who, clear, and clean sound beats muddy, and distorted every time, in every situation.
I can honestly say I’ve never had a patient tell me that they didn’t care about distortion.
That is why the input range is critical in all acoustic systems, it is one of the reasons we are proud to highlight Widex hearing aids amongst the tools in our patient tool kit. With the widest operational and greatest input range in the industry, whether you are listening for that whispered promise of things to come, or rocking out at a concert, or party, the signal comes through clean, clear and undistorted.
With their on board In Situ’ audiometric suite, we can measure anyone's hearing thresholds and begin demonstrating the real life changing benefits of crisp, clear, natural sounds to most everyone in under thirty minutes from, when they walk through our door.
So, if you, or a loved one has trouble hearing clearly in those noisy, or any other situations for that matter, if you’ve got thirty minutes, we might just be able to change your life significantly, enriching your enjoyment of all the sounds of life, whether a whisper, or a shout.
Simply drop by our office in the Heart of Historic Downtown Melbourne any weekday morning, from 9:30 till noon, when we welcome walk in visitors, new patients and just about anyone who’s curious without an appointment. Or, for more convenience, call us at 321-722-2894 and schedule a few minutes to change your life for the better.
No, obligations, charges, or hassles. We promise, just an experience we promise to be fun, enlightening and very possibly life changing.
Always; Patient Centered, and Results Oriented, it’s what we’re all about with hearing care solutions for every lifestyle and budget.
To read more about why range is important in hearing aids, and see what else is going on in our community this month, see our articles in “Spotlight on Brevard”, and “Senior Scene” magazines.