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Technology Takes Custom Hearing Aids to New Level

Hearing aids have gone through drastic changes throughout the years. In a recent article on Healthy Hearing we discussed hearing aids through the years and how they have become the tiny sophisticated digital devices of today.

With improvements in technology and digital processing, digital hearing aids have brought new levels of satisfaction among wearers and also improvement in quality of life. (Isn’t it great to hear things you’ve been missing?)

Today, consumers have many options when it comes to size and design of their hearing aids. Although the recent trend in hearing aids has been behind-the-ear open fit hearing aids, many consumers still choose custom devices constructed to conform to the unique shape of each wearer’s ear canal. Custom devices can be quite discrete which is why they are still popular among many.

The construction of custom fit hearing aids takes a precise manufacturing technique to ensure a comfortable fit for the wearer. For many hearing aid manufacturers they have been improving their process over the year to improve first time fit and satisfaction with fit. And thank to modern technology, not only has the technology within hearing aids gone digital, so has the technology to build them.

Hearing aid manufactures such as Phonak, have adapted sophisticate manufacturing techniques to ensure the first fit is optimal. The benefit? Less remakes and less visits to the hearing care professional’s office.

Science marches on. It also makes fitting a customized hearing aid a breeze.

Each Ear Canal Is Unique

The ear canal is the tube that runs from the outer ear to the ear drum. Sound is capture by the outer ear (the pina), directed down the ear canal where sound waves activate the ear drum and the hearing process begins.

Here’s the thing. Even though all ear canals are basically open tubes, each has a different shape – longer, shorter, wider, more narrow, curved here, straight there. Just one of those nature things. However, in the past, fitting a custom hearing aid was a time-consuming, sometimes frustrating process with hearing aid professionals making best guesses on physical adjustments to customized hearing aids. It was pretty much a hit-or-miss proposition.

But no more. Technology has simplified and improved the customized hearing aid fitting process the way technology is supposed to.

The Ear Impression

ear impression
Ear impression, Courtesy of Phonak

Step one of the fitting process is to take a mold of the client’s ear canal using a silicon-based putty. Very pliable, this cast is the perfect replica of the hearing aid wearer’s ear canal – the place where the custom-manufactured hearing aid will reside 14-16 hours a day.

So, comfort is key and getting the initial mold right is critical to simplifying the customization and fitting process. Be sure to work with a hearing professional with experience in customized fittings. This will insure the comfort and discretion consumers look for in a customized device.

Technology note: eventually this first step will be taken over by digital ear scanners – allowing the hearing care professional to simply scan the outer ear to create a digital image of the patient’s ear. This digital image will then be emailed to the manufacturer. Although this technology currently does exist, it is not quite “fiscally” available for most hearing care professionals and will be a number of years until the costs come down.

Technology Takes Over

Phoank 3-D Shell Design
Phonak's 3-D Shell Design

After the hearing care professional ships the silicone ear impression mold to the hearing aid manufacturer, the next step in the process involves a laser scan of the mold. The laser scan results in an exact, 3-D duplicate of the mold, in other words the laser scanner converts a 3-D image of the mold into digital data on a computer.

Once converted to digital data, the hearing aid manufacturing technician applies various options to the design of the hearing aid. For example, will there be a volume control or a vent? These options are selected within the computer software and are optimized for the smallest possible hearing aid shell.

The digital design is then sent to a digital 3D printer which actually creates the customized digital hearing aid shell using medical grade acrylic with computer controlled UV light exposure.

The result is a more accurate, faster and consistent making of a hearing aid.

Customized Hearing Aid Shells

Phonak eshell production
Photo courtesy Phonak

To the left is a picture of customized Phonak hearing aid shells being manufactured. Each shell is distinct; each configured from the computer data collected from the laser scan of the ear impression mold. The computer program tells the manufacturing equipment the exact specifications of each hearing aid shell.

Quality custom hearing aids are constructed using medical-grade acrylic to produce “a dimensionally exact, lightweight but durable shell.”

The Human Touch

Once the acrylic casing has hardened, it undergoes rigorous inspection by a manufacturer technician to insure the device casing is perfect. Using the latest in quality assurance technology, each unit is put through its paces, electronically and physically, to ensure the right fit and the right hearing gear.

In Your Ears

The finished hearing aid – the perfect, computerized fit – is now ready for your ears.

Hearing aid shells come in a variety of colors and tones to match skin color. Companies such as Phonak, are also committed to producing shell materials in a variety of colors that are hypoallergenic.

Hearing aids are typically worn the majority of a person’s day and depending upon the wearer’s sensitivity, can cause irritation. Luckily with advancements in shell material, wearers should no longer worry about an allergic reaction.

Phonak eshell colors
Rainbow of options for Phonak custom shells

Currently Phonak utilizes 8 different acrylic shell colors for their custom hearing aids – all of which are certified hypoallergenic according to independent laboratory biocompatibility testing.

According to a recent Phonak release: “Phonak’s shells received a rating of “0” on a 0-4 standard cytotoxicity scale; which is completely non-toxic. They also are rated 0 - 0.4 on a clinical dermal irritation test scale, which means they produce no or negligible skin reactions. These tests are compliant with ISO and U.S. Food and Drug Administration Good Laboratory Practice regulations.”

In a recent interview with Healthy Hearing, Diane Hammel, AuD, FAAA, Sr. Manager of Product Management, Phonak US, stated: “Phonak is committed to providing the highest quality custom products designed to maximize benefits for the consumers in all aspects of their fitting experience.”

So, if you are thinking about custom fitting hearing aids – know technology is on your side to provide you the most accurate, comfortable listening experience.

Hearing aids become part of your everyday life and they should also “feel” like they are a part of your everyday life.

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