From Foam to Global Impact: Elliott Berger on Hearing Protection

What if the simple act of inserting a foam earplug could protect your hearing for a lifetime? Join us for an engaging conversation with Elliot Berger, an acclaimed scientist and engineer whose groundbreaking work in hearing protection has transformed lives worldwide. We journey through the fascinating history of the iconic yellow foam earplugs, initially developed by Ross Gardner at Cabot Corporation, and explore Elliot's pivotal role in their global success. With billions of these earplugs sold globally, Elliot shares invaluable insights into their proper use and underscores the vital importance of correct insertion techniques for optimal hearing protection.

Gain an understanding of the complexities involved in measuring and preventing hearing loss, with a focus on fit testing systems and noise attenuation measurements. We delve into essential guidelines from OSHA and NIOSH, emphasizing the critical need for modest noise reduction and highlighting personal health strategies to avoid temporary damage like tinnitus. Reflecting on a conversation from two decades ago, we celebrate Elliot's lasting impact on raising awareness about noise-induced hearing loss, a condition that is largely preventable. This episode is a tribute to his enduring influence and a reminder to take proactive steps in safeguarding your hearing health.

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Chapters

• 0:19 Innovations in Hearing Protection Technology
• 14:26 Measuring and Preventing Hearing Loss
• 28:32 Recognizing Contributions to Hearing Health

Transcript

Blaise Delfino:

You're tuned into the Hearing Matters Podcast, the show that discusses hearing technology, best practices, and a global epidemic, hearing loss. Before we kick this episode off, a special thank you to our partners. Sycle, built for the entire hearing care practice. Redux, the best dryer hands down. CaptionCall by Sorenson, Life is Calling. CareCredit, here today to help more people hear tomorrow. Fader Plugs, the world's first custom adjustable earplug. Welcome back to another episode of the Hearing Matters Podcast. I'm founder and host, Blaise Delfino. As a friendly reminder, this podcast is separate from my work at Starkey.

Dr. Douglas L. Beck:

Good afternoon. This is Dr. Douglas Beck with the Hearing Matters Podcast, and today's guest is Elliott Berger. Elliott will be familiar to most of the people of my generation and perhaps one or two generations beyond that. He's an award-winning scientist, and Mr. Berger is a engineer. He was a Division Scientist for 3M's Personal Safety Division, and he's been with the National Hearing Conservation Association, NHCA, for a long time. He received their Lifetime Achievement award a number of years ago. In his role as acoustic engineer and researcher, Mr. Berger has done some amazing things. He was one of the folks who intervened on the yellow foam earplug, which was created by I think your boss, Elliott. Isn't that right? Ross Gardner?

Elliott Berger:

Correct.

Dr. Douglas L. Beck:

So, tell us that story because most people are familiar with the E-A-R little foamy plugs, and they have no idea where that started. Tell us how that originated.

Elliott Berger:

I was a student in North Carolina working on my master's degree. Dr. Larry Royster was my professor, and we were doing a lot of work in hearing conservation. My thesis was on noise-induced hearing loss in the textiles industry. I thought I was familiar with a lot of the hearing protection that was available. I happened across an ad in Physics Today looking for engineers with PhDs. I didn't have a PhD. It happened to list acoustics way down the list. I thought I'd apply, and lo and behold, they looked me up. It was the company that was beginning to manufacture yellow foam earplugs and other noise control materials. We got some in the lab before I went up for my interview and showed them to Larry and said, "Hmm. Foam doesn't block sound. I don't think these could work all that well." We thought, "Well, maybe." I went up there and was interviewed. This was in 1976, and Ross Gardner was the fellow who interviewed me. He was-

Dr. Douglas L. Beck:

He was a chemist.

Elliott Berger:

... a bachelor's degree chemist. He'd been working for a company called National Research Corporation, and they had a number of interesting projects. His project was on joint sealant compounds, so he was looking at flexible materials that could be used to improve highways and make sure things didn't deteriorate. He realized that they had energy-absorbing characteristics, so he asked them if he could branch out. Another company then purchased it, Cabot Corporation, and he started working.

Dr. Douglas L. Beck:

Oh, sure. Cabot, and that was E-A-R right there, right?

Elliott Berger:

Cabot owned E-A-R. E-A-R was a subsidiary or division of Cabot at the time. He started looking at these energy-absorbing resins, which is where E-A-R the acronym came from, and was primarily looking at damping materials. So something you would put on a resonant metal surface so that when you applied it couldn't ring and it wouldn't make as much noise.

Dr. Douglas L. Beck:

Sure.

Elliott Berger:

Those materials are still used widely and sold today, but a fellow came into their laboratory who was promoting another type of earplug because Ross had had some renown in the area around Boston, Massachusetts, heart of a lot of acoustics research. He wasn't much impressed with that earplug that the fellow showed him, but it got him thinking. He said, "Well, how can I put this blue stuff that I'm making into my ear to block sound?" It was a very dense, rubbery-like material, and getting that in your ear, not going to work.

Dr. Douglas L. Beck:

Yeah, good luck.

Elliott Berger:

So he put a foaming agent in it and turned it into a foam version of that damped material and then started working with it. Hence, that's where the yellow foam earplugs arose. I was actually hired to do research and promote the noise control damping materials, the solid blue materials, but shortly after I got there, the company at that time, I was the 13th employee, so it was not a lot of activity there. There were only three of us in the lab, and it became clear that the foam earplug needed a lot of research and development, fine-tuning and promotion. So, very shortly that became the focus of my activities, and that was the job I held for 42 years. I did things other than yellow foam earplugs, but that was the beginning.

Dr. Douglas L. Beck:

They're sold universally around the globe. How many hundreds of millions have been sold?

Elliott Berger:

Today, I couldn't tell you that number, but it's more like in the billions.

Dr. Douglas L. Beck:

Yeah, I would bet. Then you get a portion of each one, right?

Elliott Berger:

I wish.

Dr. Douglas L. Beck:

Hey, listen, but I know that your video instructing people how to properly insert them in their ears, it had over 500,000 visits last time I saw it. This is my constant journey in life. Sometimes when I'm at airports, and I see the guys walking through the airport with their hearing protection, I'll stop them and say, "Hey, I'm an audiologist. I'm really glad to see you wearing that hearing protection. Let me give you a hint. You have to really roll it up tight, tight, tight." I try to instruct and help them. Sometimes they say thank you, and sometimes they say, "Mind your own business." But nonetheless, Elliott, because you are the world's expert on this, show us how to do this properly.

Elliott Berger:

Well, I just happen to have a pair handy, and the pair I pulled out of my drawer, actually, this is the original packaging.

Dr. Douglas L. Beck:

Sure.

Elliott Berger:

So, this pair of plugs could well have been made 20 years ago. They last forever on the shelf. One of the very interesting creations that went along with this plug was this packaging called the Pillow Pack, which at the time was unique and helped it sell as well because it was a good way to deliver the product. As you mentioned, and I've done the same thing. I often grimace. I see people not wearing it well. Every once in a while, though, really, I'd say more often an engineering type is the person who will have learned how to roll a plug down correctly without any intervention.

Dr. Douglas L. Beck:

Right.

Elliott Berger:

The deal is that, let's see, you want to roll it into a very tiny, tightly compressed cylinder, so it's like a little pencil, if you will. I'm trying to get this right in the camera. As you roll it, you want to squeeze it harder and harder as you roll it more, but you don't want to press hard initially because this isn't like a bathroom sponge. I don't want to mash it up or knead it. I need to have a very smooth cylinder with no creases or wrinkles. So by the time I get this thing rolled down, I am literally squeezing it as hard as I possibly can. I'm not going to damage the foam. This is what I want it to look like, a tiny tightly compressed cylinder.

Dr. Douglas L. Beck:

It just takes five to 10 seconds to do that.

Elliott Berger:

Correct. Then the other key is that you are going to pull your ear upwards and outwards. I just was watching a video the other day, and unfortunately ... It was a government video, reasonably well done, but it had two key mistakes I would say. One is they talk about pulling the ear back, and I found that for most people out and up is more likely to straighten the canal.

Dr. Douglas L. Beck:

Right.

Elliott Berger:

If you're assisting someone like you like to do, I would say that ask them to pull the ear while you're looking at it because for people it may be straight out. It could be down. It isn't always an up and out, but that's the most common.

Dr. Douglas L. Beck:

It is, and in fact, if you pull it back, a lot of times you're closing the ear canal because your tragus will fold over on it. Yeah.

Elliott Berger:

Absolutely. As you're doing this, you want to keep rolling the plug. As you bring it up to your ear very quickly, then slide it in. I'm wearing hearing aids, so I'm not going to slide this into my ear. Actually for viewing purposes, why don't we do that? So you would like to get it so the plug is in your ear, and for most people it should be behind the tragus, so you can touch it with your finger. You could take a picture with your telephone, do a selfie and see. If most of the plug is behind the tragus, it's a reasonable indication that it's a well-fit plug. It's not a certainty because the distance from the tragus to the canal entrance-

Dr. Douglas L. Beck:

Varies, sure.

Elliott Berger:

... varies person to person. One other thing that it's not a problem, but in most videos they will then say, "Got to hold it for 20 to 30 seconds."

Dr. Douglas L. Beck:

No, you don't.

Elliott Berger:

That's a bunch of stuff. The reason people say that is because often the plug appears to expand out of the ear canal. It isn't actually doing that. The plug, as I mentioned, gets rolled down and compressed into a tiny cylinder. When I put it in my ear, if I didn't put it in correctly, I would have shortened the plug lengthwise, and no amount of holding it for 10 seconds or 10 minutes is going to keep it in the ear at that point. When I let go, it's going to regain its original length. So holding it gives you a false sense of security, and it wastes time. You put it in, you let go, it will expand radially outwards. I'm not sure if you can see. Does that?

Dr. Douglas L. Beck:

Yeah, that looks great. That's perfect.

Elliott Berger:

The other thing you can do is it's been in my ear now for what, a minute or two?

Dr. Douglas L. Beck:

Sure.

Elliott Berger:

I'm going to take it out, and you can see the shape of my ear canal. What I want is that about one half of it or three-quarters was in the ear. I don't want to see any folds on the plug. I don't want to see any creases or sound channels along the plug. So, my video is still out there because it was put up some years ago. It doesn't get as many hits today, but between the American and European versions, there's about three-quarters of a million people who've looked at it, and I would suggest you find that one for the best discussion.

Dr. Douglas L. Beck:

Absolutely. Yeah, that's going to be better.

Elliott Berger:

Unfortunately, this camera didn't really pick up all the details. You'll be able to see a lot more.

Dr. Douglas L. Beck:

That's okay. They get the idea, and I think it's important to have a little guidance there. Elliott, when the E-A-R plug is correctly placed in your ear canal, what is the typical NRR, noise reduction rating?

Elliott Berger:

The NRR for foam earplugs is typically about 29 dB. It can vary depending on the laboratory that's doing the work. That NRR is for a well-fitted plug optimally fitted in a group of experienced laboratory subjects. A lot of my work had to do with looking at real-world performance of hearing protection, and that unfortunately can be much less. Foam earplugs tend to be more forgiving than some other types of insert hearing protection because of the fact that they're expanding to seal the ear even if they aren't fully inserted, but the real-world NRRs can be much lower, something more or less in the teens. Something that I worked on starting in the early 2000s and helped promote that 3M brought to the world was a fit testing system called E-A-Rfit.

Dr. Douglas L. Beck:

Yeah, tell us about that. Yeah.

Elliott Berger:

There are a number of fit testing systems available today. The unique feature of the E-A-Rfit is that it uses a surrogate earplug. So you would take one of these yellow foam earplugs, and there'd be a tiny little flexible tube through it. When you put the plug in the ear, that tube then hooks up to a measurement microphone. You sit in front of a small loudspeaker, which plays sounds for about 10 seconds. Then you immediately have an estimate of the noise attenuation of that device at all frequencies.

Dr. Douglas L. Beck:

So in some regards, it's like a real-ear system. I mean, you're measuring NC too behind the plug closer to the eardrum.

Elliott Berger:

Absolutely. Good analogy. The other common types of fit testing systems will put large noise-excluding earmuffs on a person and give them an audiogram with and without the hearing protector. Of course, that's essentially how you measure attenuation in the lab, except you're doing it in a sound-controlled room with very precisely calibrated instruments. But the gold standard in measuring noise attenuation for hearing protection is called real-ear attenuation at threshold. So that means you give a person an audiogram with and without the hearing protector. Obviously, if the hearing protector has done its job, it's going to raise their threshold levels, and the difference between them is the noise attenuation of the device.

Dr. Douglas L. Beck:

It's important to understand that even if you're getting 15 to 20 dB attenuation, that may not sound as impressive as 29, but it's often quite enough. The way that noise protection and noise damage occurs, if we use OSHA guidelines, which were not written for music, and they're not perfect, but it gives you the idea. So at 90 decibels for eight hours, if one were to listen to 90 decibels for eight hours, that would cause hearing loss. The way it works is it trades off time versus loudness. So with regard to attenuation and NRRs, 15, 18 dB attenuation may not sound like much, but it's actually quite a bit. When we think about how much noise causes hearing loss, we have OSHA rules, and then we have NIOSH guidelines. I'll talk about the OSHA rules to make it simple. Then Elliott, if you'll talk about NIOSH.

What happens with OSHA, the Occupational Safety Health Administration, they said that 90 decibels for eight hours will cause hearing loss, and there's a 5 dB trade-off. So, when you go up to 95 dB, you can only listen for four hours before it causes hearing loss. At 100 dB, two hours, 105 dB, one hour, 110 dB, 30 minutes, 115 dB, 15 minutes, et cetera. So when you're lowering that by 15, 18, 20 dB, you can see you add quite a bit of time before damage occurs. Those are the OSHA guidelines, and they were written not for music or anything like that. They were written for industry and military purposes, and those are the rules. Those are the legal rules, but then the NIOSH, the National Institute of Occupational Safety and Health Administration, those are probably more accurate. Can you talk about those, Elliott?

Elliott Berger:

So OSHA is the enforcement arm, if you will, of the government. NIOSH is the scientific research arm that informs government agencies and informs the public. What their recommendations are is an 85 dB eight-hour exposure with a 3 dB trading relationship. So you can see the allowable duration of exposure diminishes much more quickly because now you go from 85, eight to 88 for four hours to 91 for two hours. It drops down much more quickly, however you look at it. You mentioned that 15 dB is really adequate for many exposures. Indeed, that's one of the things that I had talked about for industrial noise. In most cases, 90% of occupational noises have an exposure less than 95 dBA, equivalent eight-hour exposure, so you don't need huge amounts of protection. 10 dB of reliable protection in most occupational exposures will give you what you need.

For a concert, 10 or 15 dB is going to be quite adequate for most people. My review of the literature suggests that typical concert or nightclub levels are in the range of 100 to 105 dB maximum. If you're up near the speakers, it can certainly be pushing 115 or 120. 15 dB is going to get you a lot of the protection you need. One of the things that I like to point out is that as a individual, you can take charge of your own health in this regard by using some listening tips. One of the things that happens when you're exposed to noise is that after the noise, you may have temporarily irritated the inner ear, and that will be reflected in something called tinnitus, which are sounds that you hear in the absence of actual sounds around you. Many people have experienced this from time to time. Hissing, humming, roaring, ocean-like sounds ringing in their ears.

Dr. Douglas L. Beck:

Sure.

Elliott Berger:

So if your ears are generally quiet, you go to a concert, you come home that night, and your ears are ringing, that was an indication that you overexposed your ears. Most people, if that happens from time to time, they will recover from it. It is possible that a one-time exposure, the tinnitus is not going to go away, but usually it's an indicator. So, you don't want to repeatedly experience tinnitus.

Dr. Douglas L. Beck:

On that same topic, when you have that temporary tinnitus, which could last overnight or into the next day, you might also have aural fullness, A-U-R-A-L, meaning your ears just feel full. You might also have some dizziness, and you might have some temporary hearing loss. All of that's referred to as temporary threshold shift. As you mentioned, very important. Sometimes it becomes permanent, so that exposure, you don't need multiple exposures. Some people get one exposure, and their hearing does change substantially, and they have all sorts of hearing and balance and tinnitus problems. So, I'm glad you mentioned that. That's great.

Elliott Berger:

So, the listening for after effects, whether it's the aural after effects that Doug talked about or the tinnitus, anything that's changed about your sense of hearing afterwards is an indicator. Another way to tell if sounds are going to be potentially hazardous is if you have to talk loudly at arm's length to be able to communicate with somebody. That's an indicator that the sounds are around 85 dBA. Again, long-term exposures are going to put you at risk, but let's keep in mind when we say 85 dBA as a eight-hour risk guideline. That doesn't say that everybody exposed, and it's based on occupational repetitive exposure. So, it's difficult to extrapolate this to short-term exposures for individuals in their daily lives because all of the data we have are based on eight-hour-a-day, 40-hour-a-week exposures repetitively at those levels.

Dr. Douglas L. Beck:

Yeah, and it's constant noise source. It's repetitive, but it's also constant. It's eight hours of not letting up, and very few people would actually do well in that environment. Elliott, if you don't mind, let me switch topics. I think it's one that's particularly interesting to me. As you know, I was in the Air Force 100 years ago and in boot camp then. That was really my first exposure.

Elliott Berger:

You're not nearly that old. Come on.

Dr. Douglas L. Beck:

Well, pretty close. That was my first exposure to weapons fire. Since then, I've got a couple of different handguns that I target shoot with, and I enjoy target shooting. Normally what I do is I will wear those little foamy plugs that you demoed, and I'll put a set of earmuffs over them because the sound, it's hard to say how loud is a 9mm Glock. The reason it's hard is it depends. How did you measure it? Which scale are you using? How far was the microphone from the gun? Did you fire it 25 times and take an average? Did you fire one time? What was the acoustic environment? Was it indoors at a range? Was it outdoors? All those things matter a great deal, but what doesn't matter is that it's very, very loud. So given small arms fire or weapons fire, what's your recommendation?

Elliott Berger:

The first thing I want to point out is that unlike the music exposures or occupational exposures, the impulse noises are much more challenging. The risk, determining the risk criteria, there's much variability between the three most prominent models. In fact, Greg Flamme, who's done some of the leading work in that area, published a paper looking at what are called maximum permissible exposures, the maximum number of unprotected exposures at a given level that would cause hearing loss in the majority of the population exposed. For certain types of impulses, the predictions vary by a factor of 1,000. For example, for one of the firecrackers he looked at, one model would say you could be exposed to 20 exposures without any risk. The other model said you could be exposed to 200,000 exposures without any risk, and it varies depending on the type of impulse. For a 30-aught-6, all of them say one impulse, story over.

Dr. Douglas L. Beck:

30-aught-6, for those who are unfamiliar, is a very loud shotgun.

Elliott Berger:

Dan Johnson was a leading researcher with the Air Force for many years, was responsible for a lot of the hearing loss standards. One of the analogies he used was that the issue of being exposed to a gunshot was like dropping a glass on a table. You might drop it six or seven times, nothing happens. The next time, the way it hits, it shatters, so there's that risk.

Let me just mention briefly the ideas about how we lose our hearing due to impulse noise. So the common thinking and the data we have available suggest that for steady noises, occupational noises, music noises, the principle cause of hearing loss is metabolic exhaustion of the inner ear hair cells. They can't keep up. They create reactive oxygen species and toxins, and they end up not being able to continue functioning, so slowly they will die off with time. With high-level impulses above about 135 dB, the thinking is that in addition to that metabolic exhaustion, the more serious issue is physical damage where the hair cells will be simply torn from the basilar membrane. At that point, obviously non-recoverable, immediate permanent hearing loss. So, you really need to be careful around impulses.

I certainly support your approach of dual protection. If you're on a firing range, that would be the best approach because there's many rounds you're going to be exposed to, and chances are for communications, you will be able to get by. However, you may find that maybe you can't hear the range commands. You can't talk to the person next to you, so today, one of the very good options would be to get an electronic hearing protector, and make one of those two hearing protectors you're wearing be the electronic one so that it will broadcast some sounds into the ear between the gunshots and allow you to hear more clearly. The downside is, of course, instead of spending $5 to maybe $50 for a passive hearing protector, one that doesn't have electronics, you're now in the $150 to a few hundred dollars range for many of these devices.

Dr. Douglas L. Beck:

Yeah, exactly.

Elliott Berger:

If you're out hunting, I would suggest that a single electronic hearing protector may well be your best option.

Dr. Douglas L. Beck:

Well, this is pretty fascinating, and it reminds me. In an analogous world, I'm a musician. I can remember so many years ago, all my musician friends would look for the Maxell tapes that were flat out to 40,000 hertz or TDK tapes or BASF, flat response out to 40,000 hertz. They would say, "Oh, yeah. I can hear the difference between the 20,000 and the 40,000." Human hearing is 20 hertz to 20,000 hertz, and you really can't hear at 20,000 hertz. It would have to be 140 dB or something. You'd feel a chest compression before you'd hear that sound, but they would swear that they could tell the difference.

This to me is also analogous to the people who say, "I like vinyl better than CDs," right? You have that shh, shh, shh going on. I can understand the emotional attachment to vinyl because that was your youth and all of that stuff, but it never sounds better than a CD. The dynamic range of a CD is almost 90 decibels versus vinyl, which is 30. Anyway, these are phenomena that you have to understand that when you're looking at hearing protection devices, the air conduction limit should not be stated 35 or 40. That's going to be bogus.

I know our time is up, and I am so appreciative of you coming out of retirement for an hour here to speak about noise reduction and hearing protection, Elliott. You're a joy to know. I remember you and I did an interview. I have it here. It was March 2005 on Audiology Online back when I was the President and Editor-In-Chief of Audiology Online. It was titled Interview with Elliott Berger, MS. Senior Scientist for Auditory Research at E-A-R, Aearo Company, Editor of the Council for Accreditation and Occupational Hearing Conservation Hearing Conservation Manual, 4th Edition. That was 2005, so that was just about 20 years ago.

I remember you fondly from that interview, and I had such a great time. I learned so much from you, so I want to thank you for your ongoing work in this area. I think it's so important as we become more and more aware of hearing loss and in particular noise-induced hearing loss, which is almost always avoidable. I think that when people take this seriously and they take your guidance to heart, their quality of life has improved substantially.

Elliott Berger:

Thank you very much, and thanks for your good memory. You reminded me about that 20-year-old interview, and hopefully we talk again before another 20 years. I'm not sure what that'll look like for both of us.

Dr. Douglas L. Beck:

I'll look forward to it. Thanks so much, Elliott.

Elliott Berger:

Take care. Bye-bye.