I have a patient that wants to know why hearing aids only last about 5 years. I explained to him about moisture and wax but that was not a satisfactory answer to him. His argument was that cars can last longer than 5 years (and are exposed to moisture), he has a titanium knee that should last 40 years, and we can send things up in space that last longer. Please suggest an explanation that I can give as to why the life of hearing aids hasn't changed over the past 15 years (the last time he tried hearing aids 15 years ago, he was also told they would last 5 years).
Thanks for the email and I think this is a fair question. There were a couple of things that I thought about when answering this question. Some of this relates to making the correct comparison between devices.
I would not compare a hearing aid to car. A car weighs several thousand pounds and has a metal and glass exterior that protects the various interior and sensitive parts of the car. It has a metal frame inside of that metal and glass exterior to further protect those interior parts. It also has various shock absorbers and springs to minimize internal vibrations from the external changes in the road. The parts that do easily wear out are typically replaced on a regular basis including various engine fluids, tires, break pads and windshield wipers.
I would not compare a hearing aid to a titanium knee as the knee does not contain any electronics that have to work over time. The knee does not have delicate electronic parts to expose to the bodily fluids around it. The knee is not made of thin plastic, the knee is made of titanium, one of the lightest and strongest metals on the planet.
Many GPS satellites have a life expectancy of about 10 years. They also are very large and weigh hundreds to thousands of pounds. We spend millions of dollars to get them into space. They consist of outer metal shells that are built to withstand the various g-forces that are experienced during launch and the harsh environment of space. They are large and have redundant electronic systems to ensure the satellite will continue to work, even if one of the systems fails.
A hearing aid is weighs only a few ounces and is smaller than your finger. It has a shell that consists of a very thin layer of plastic as the components can barely fit inside it. The hearing aid has miniature and delicate microphones, some of the smallest in the world, that allow sound to be picked up and amplified. Ditto on the wide bandwidth miniature speaker. There is no room for bulky or redundant electronic components. There is however a highly engineered digital signal processing unit that has more computing power than some of the early NASA rockets. All of this is configured to run on around 1 volt while producing outputs in excess of 100 dB SPL in the ear canal.
As I mentioned above, the question is fair, but your patient is comparing oranges to apples. I will admit though, that I have still not answered why hearing aid technology has not progressed to last longer than about 5 years.
Based on my opinion, this is because the market has not demanded it. Over the past 15+ years what patients have demanded is something smaller, something discrete. Start back around the middle part of the last century and then move forward all the way to today, take a look at the advertisements and see what was being promoted. "Virtually invisible" and "No one knows I'm wearing one" are the catch phrases. Engineers worked to continually create devices that were smaller in size, larger in output range and bandwidth and computational power while minimizing the amount of battery drain. These advances have helped to make smaller more powerful hearing aids, but they have not become any more durable.
That said, over the past couple of years there have been advances in things such as microphone covers and coatings on the body/shell of the hearing aid to resist moisture seeping inside (such as in the seams of a BTE case or the opening of the microphone inlet). I have heard about actual coatings that can be applied to the microphones and receivers themselves - making them highly water resistant. This has been in response to more and more active users requesting more robust hearing aids that can work more effectively in those environments. So, these advances are coming and should help increase the life of the hearing aids compared to current devices.
Regardless of the life expectancy, I am not sure that I would want to wear a hearing aid that is older than 5 years on a regular/daily basis. A good analogy is a computer. I use a computer all day long every day. If I had to use a 5 year old computer today, it would work, but, it would be slow, it would not be able to perform certain functions, it would hamper my ability to really perform my job the way I should.
The same thing with a hearing aid. Take a look back 5 years ago at the hearing aid technology that was available. The top of the line hearing aid from back then is maybe an entry level device or may not even be available today. New hearing aids are coming out about once a year and so after 5 years, your hearing aid is 5 generations behind the latest technology.
Getting back to the car analogy - new hearing aid models are coming out each year, but new car models come out once every five years or so. I would argue that the development cycle of hearing aids are much more rapid than a car. So where a car that is 5 years old, may not be that old, as you know - a 5 year old hearing aid is really old.
Can a patient still wear and use 5 year old hearing aid technology? Absolutely! Would they want to? This is a question that would need to be answered by the patient working with their Audiologist. When I was in practice, I was happy to help my patients with the upkeep of their current (old) hearing aids. I also made sure I educated them with the new advances in technology to keep them informed. I always liked to give them options.
Well, I am not sure if this long winded answer helped with your question, but I hope that you continue to dialogue with this patient to find the best solution for him or her.
Dr. Paul Dybala is the President and Editor of Audiology Online, the world leader in online hearing health education and information.