Dr. Bob Martin
This post finishes Dr. Bob Martin’s 10 blog series, see where it all began with Part 1 on “Winning the War Against Hearing Loss.” Three posts on Migraines to follow…
We live in a wonderful age of constantly changing electronics. This robust technological environment benefits us personally and professionally. The hearing aids we offer patients with hearing loss today are dramatically better than those we dispensed when this century began.
When I started this series back in June, I promised to discuss the technology behind the “miracles.” So far, I have talked about signal detection, speech intelligibility, feedback cancellation, and other areas. Today, let’s talk about real-ear mechanics.
Real-Ear Mechanics
I learned a lot about ear mechanics when I purchased my first real-ear system. My initial discovery was that my existing hearing aid fittings were ugly. The response included large unwanted peaks and valleys. At first, nothing made sense to me. It took me years to fully understand how the “ear” works and how sound changes when it is routed through an ear canal.
Putting a standard hearing aid or earmold into an ear changes the mechanical properties of the ear significantly. If you want to appreciate this concept, do the following experiment:
- Say the sound “Shhhhhhhhhh” for 20 seconds.
- While saying “shhhh,” put your fingers into your ear canals (gently, not tightly).
- Listen to the level of the sound decrease.
- Remove, and then replace your fingers.
- Repeat this exercise.
Putting your fingers in your ear canals (not too tightly) destroys your ear canal resonance. You should hear a large change in the sound “shhhh” you are making. You hear the sound loudly before you insert your fingers. The sound diminishes markedly when you insert your fingers slightly.
In a similar fashion, putting a typical custom hearing aid in an ear changes the mechanics of the ear. Said differently, when you fit a conventional hearing aid, the first thing you do is make the hearing problem worse and more complicated by changing the ear canal resonance. Everyone who does real-ear testing understands this concept.
There’s No Substitute for Measuring
Prior to purchasing real-ear equipment, I lived under the delusion that I could predict the amount of sound lost through a vent. I quickly learned the foolishness of this belief. The only way to accurately evaluate the sound in an ear is to measure it.
This concept was true 30 years ago, and it is still true today. If you believe that your hearing aid fitting software is giving you accurate information about real-ear response, you are making the same major mistake I made years ago.
All of us in the hearing aid industry spent years debating questions: “Which fitting formula is the best? Should we restore equal loudness curves? Should we focus solely on word understanding? How do we make new patients comfortable?” But these were the “wrong questions” to be asking.
Using Real Ear to Find and Answer the Right Questions about Correcting Hearing Loss
The most important lesson we learned about new users was, “If you give patients the amount of sound they need, they will probably reject the hearing aids.” Looking back, this is obvious. At the time, we all debated the approach.
This was a difficult period in our professional history. We all thought our approach was correct and we firmly believed people who took some other approach were wrong. It turns out we were all wrong.
We all had to learn to compromise. We also had to learn to program amplification specifically for each listening situation. The type of amplification you give someone for a quiet office is not the same sound you give that patient for a noisy restaurant.
Sound Engineering Improves Amplification
There are many specialty fields in sound engineering, including signal transmission, signal detection, feedback cancellation, adaptive software, and artificial intelligence, just to name a few.
These topics are now finding their way into hearing aids. The results are spectacular! In the exhibit hall at a national convention earlier this year, a hearing aid manufacturer was demonstrating the effectiveness of its new product’s noise cancellation by turning on a hair dryer and moving it around the head of a person who was wearing the hearing aids. The hearing aids were “smart” enough to find the moving noise and cancel it.
This type of technology is staggering. Thank goodness, hearing care is not the only profession interested in sound. Some of the largest research budgets in the world—those of the military and major industries–are also devoting extensive resources to sound. We benefit from their research.
FINAL THOUGHTS ON “WINNING THE WAR”
There is a take-away lesson from my 10-part series on “Winning the War Against Hearing Loss,” which this week’s article concludes.
The amazing advances you hear about in medicine and other health care professions are happening in hearing care as well. We, like other professionals, create miracles. We save people’s lives. We return unemployed people to work, empowering them with the ability to hear. We repair marriages damaged by communication problems and enable people to resume social activities that their hearing loss had precluded. And, every year, hearing aids introduce huge new improvements.
The most important news I want to share with you is this: The best is yet to come!
We are just a few years away from fitting hearing aids that totally eliminate background noise. The frequency transposition of speech cues will get much better. Bluetooth transmission will bring in clearer, noise-free signals. And, as these dramatic improvements are taking place, hearing aids are getting ever smaller and more patient-friendly.
I want to close with one last thought: The kinds of miracles that I have been writing about over the past year will not happen if we simply give our patient a fantastic hearing aid in a box.
Hearing aids are computers, and, just as in industrial applications of computer software, they will not be successful unless skillful professionals mold, shape, change, and adapt the hearing aid’s programs to a specific patient and situation.
We are as close to having “auto fit” hearing aids as out-of-the box computers are to conducting research and design independently. Said differently, hearing aids can’t do it alone. They need to be fitted by a skilled professional, and they must be custom-fitted to a specific patient. Hearing aids also need to be modified for specific listening conditions–in noisy restaurants, near barking dogs, in school classrooms. They need to be programmed so that the amplified sound they produce is comfortable, and hearing aid wearers need to hear well across distance.
As hearing aids continue to improve and become more sophisticated, our job becomes even more important, and our patients need us to do more. We are often asked to perform miracles. And, thank heaven, many times miracles are possible.
