3M Science of Safety Global Podcast

Global Science of Safety Podcast: Hearing Protection Part 1

In this episode of the global Science of Safety Podcast, co-hosts Mark Reggers and Laurie Wells along with guest Mohammed Saleem, a Senior Application Engineer with the 3M Personal Safety Division in the United Kingdom discuss some fundamental concepts for hearing protection selection. This is part one of a two-part series on selection.

Do you realize that noise is one of the few occupational hazards that also exists in our everyday world outside of the workplace? That is why it is important for people to know how to choose and use hearing protectors.

Tune in to hear more about:

  • How do hearing protectors work?
  • What makes them different?
  • How should employers select them and
  • How to ensure they are providing the protection needed to keep people safe from loud sound. 

This global podcast series provides another educational tool that can help increase your knowledge and is something that you can share with others in your organization and with your friends. The goal is to help provide a global perspective and foundation for those of you new to workplace health and safety and personal protective equipment (PPE) while also providing information for more experienced professionals and complex health and safety challenges.

You can listen, subscribe to, and share this podcast through Apple Podcasts, Spotify, Google Podcasts, Stitcher, and most major podcast apps and platforms.

If you have any questions or topic suggestions, you can get in contact with this podcast by contacting your local 3M office or visit our worker health and safety website. If you’d like some assistance in your workplace when it comes to the appropriate selection, use, and maintenance of PPE please contact us today.

This year the Personal Safety Division is also celebrating the 50-year anniversary of the first U.S. Government-approved 3M filtering facepiece respirator (a precursor to what is now known as the N95), and the 3M™ E-A-R™ Classic™ Earplug. To all of our customers who have trusted 3M brand PPE between then and now, thank you.

Around the world, we aim to help everyone get the job done safely today, tomorrow and in the future.

Below is the full transcript of the podcast:

Speaker 1:                         

The 3M Science of Safety Podcast is a free publication. The information presented in this podcast is general only, should not be relied upon to make specific decisions. Listening to this podcast does not certify proficiency in safety and health. You should always seek the advice of a licensed or certified professional in relation to your specific work or task. Always consult the user instructions for any personal protective equipment you are using and follow local laws and regulations. Information presented is current as of the date of the podcast and requirements can change in the future. 3M owns all rights to the podcast and any reproduction is strictly prohibited without permission.

Mark Reggers:

Welcome back to our previous subscribers and new listeners. The Science of Safety Podcast is presented by the 3M Personal Safety Division. This is the podcast that is curious about the cience and systems behind workplace healthand safety, with the focus on personal protective equipment, or PPE, used to help keep workers healthy and safe. I am Mark Reggers, one of your co-hosts. I also have Laurie Wells with me. We are occupational health and safety professionals who like to ask the questions, why, how, and please explain. Whether you’re a safety professional, occupational, or industrial hygienist, someone with any level of worker health and safety responsibility in your workplace, a user of PPE, or a health and safety nerd, this is the podcast for you. Now, Laurie, I know you’ve been waiting, not so patiently, for our podcast on hearing protection. I know you’re very eager for all of us to talk about some of the specifics about how to hearing protectors work, what makes them different, how should employers or workplaces select them, and how to ensure that they are providing the protection needed to keep their workers and people safe from loud sound.

Laurie Wells:

You are exactly right, Mark, I have been looking forward to this topic because finally, today we have the chance to explain some of the science behind protecting workers from hazardous sound. It’s interesting because noise is one of those few occupational hazards that also exists outside of the workplace in our everyday world. So, it’s really important for people to be able to identify hazardous noise, and then know how to protect themselves by choosing and using hearing protectors.

Mark Reggers:

I think you’re really spot on. A lot of people don’t appreciate, but you’re right. Typically, noise-induced hearing loss has been associated with noise at work, but actually there’s noise everywhere. And of course, people choose to listen to loud music and do noisy things all the time, at home, recreationally. Now, I notice you use the words, “sound” and “noise”. What’s the difference between
them?

Laurie Wells:

Well, let me ask you a question. I’ll turn it around to you, Mark. What is noise to you?

Mark Reggers:

Well, there’s actually this kid down the street that he walks by our house with a boombox blaring some awful music. Now, that is noise to me.

Laurie Wells:

Yeah. Understandable. So, it’s noise to you, but it’s a wonderful sound to him. So, it turns out that it’s not always so simple to differentiate the difference between sound and noise. But there is a simple definition. Noise just turns out to be the sound that you don’t want to hear.

Mark Reggers:

So, one person’s treasure is another person’s junk or vice versa. So, example, one person love to listen to techno music, the kid down the streets, and the other hates it, maybe me?

Laurie Wells:

Yep, you’ve got it. So, the key really is to know, either it’s sound or noise, at what point is it hazardous? And that really depends on the combination of how loud it is as well as how long you are hearing it. And there’re different ways to measure that. And in most countries they have a level that’s set. Then, you’re allowed to listen to the sound up to that level for a certain amount of time. But there’s a trade off. If you get louder, you have to cut your time in order to compensate for that extra loudness. So, most of the countries in the world set the limit at 85 decibels, and they use a 3dB trade rate or exchange rate. So, if you go up by 3dB, you’ve got to cut your time of exposure in half in order to maintain an equivalent exposure. So, 85 … Yeah, you do the math, Mark.

Mark Reggers:

So, I was going to say, so if I’m doing this right, 85 decibels, or dB, for eight hours, is the same exposure or dose as 88 dB for four hours and 91 dB for two hours, etcetera, etcetera. Is that how it works?

Laurie Wells:

Yeah. Yep, absolutely. So, you can see that as you get up to those louder and louder levels, you have shorter and shorter time that you can safely be exposed to that sound. So, let’s say you get up to a 100 dB, you only have a few minutes, really, of allowable exposure.

Mark Reggers:

I suppose that’s a bit like our previous discussion about respiratory protection is, it is as important to know what work is hazardous in order to choose the appropriate PPE.

Laurie Wells:

Yes, exactly. So, when it comes to the workplace, there’s noise, but there’s also, potentially, some other environmental factors that put hearing at risk. For example, there are some chemicals that are toxic to hearing. So, there are certain solvents and asphyxiants. So, it gets complicated in knowing exactly what the hazard is and how to measure it. And I’m thinking this is a really good time to bring in one of our esteemed colleagues from the UK. I’d like to say hello to Mohamed Salim. Hello, Sal.

Mohamed Saleem:

Hello, Laurie, and hello, Mark. Good day to you both.

Laurie Wells:

Sal, thanks for joining us today. For the listeners, Sal is one of our most experienced 3M application engineers. And he brings us extensive experience in occupational health and safety, both in respiratory and in hearing protection. Sal, why don’t you tell our listeners a bit more about your professional background and what your role is at 3M Personal Safety Division?

Mohamed Saleem:

Sure. My background, I’m a certified industrial hygienist with a Master’s degree in Occupational Hygiene, from Newcastle University in the UK. I’ve been with 3M for over 30 years, and I’m currently one of the application engineers responsible for supporting our hearing business across Europe, Middle East, and Africa. I work closely with our customers helping implement an effective PPE program in the workplace. In addition, I am actively involved in European CEN and International ISO Standards Development Committee in helping create good science-based product performance standards.

Laurie Wells:

Excellent. Well, I know you know a lot about this topic, Sal, and we were just talking about how does the employer really know what the hazard is, how they measure the hazard in order to appropriately select hearing protection. So, maybe you could expand a bit about that. How does the employer really go about knowing more about noise exposure?

Mohamed Saleem:

That’s a great question. Knowing the exposure is really important for a number of reasons. First, the employer needs to know whether or not there is a hazardous noise present in order to determine if a formal hearing loss prevention program, or sometimes known as Hearing Conservation Program, is needed. Secondly, when hazardous noise is identified, the employer needs to know what actions are to be taken. The first obligation of the employer is to apply what’s called “the hierarchy of control”.

Mark Reggers:

That’s something we actually discussed previously in the Respiratory Protection Podcast. So, it’s right to know that top priority is to eliminate the hazard, no matter what the hazard is, which is noise in this case what we’re talking about.

Mohamed Saleem:

Yes, eliminating the noise, controlling the noise through engineering or administrative methods. And finally, if a noise cannot be reduced to a safe level, then the employer must provide hearing protection devices. So, you were asking about how to know if there is a hazard hazardous noise. And actually, a very simple trick is applying what we call “arms length rule” or “general rule of thumb”. If you need to raise your voice to be heard at a distance of approximately two meters, then you are probably above 85 dB. And if you need to raise your voice to be heard at one meter distance, then the noise level is likely to be above 90 dB. That gives a guideline. That is simply a guideline, but employers need to be specific with regards to the information about the sound level and the frequency content of the sound. So, there is a specific way to measure the noise using specialized sound measurement equipment, like the sound level meter or the personal noise dosimeters. A sound survey is done in order to quantify the level of sound where the worker stands, and also to measure the equipment and the work
processes.

Laurie Wells:

So, they have to understand how loud the sound is, how long that they’re in the sound or working in that particular noise. And here in the US, I’ve noticed that there’s a lot of sound level meter apps that are available. What about in other places in the world? Do you ever see these sound level meter apps being used in the workplace?

Mohamed Saleem:

Actually, there are some good ones around these days. And they can be used for general information, but here in Europe, we aren’t able to use these for meeting our regulatory requirements.

Mark Reggers:

That’s very much the same here in Australia. I personally mostly find them useful for training purposes. They’re really powerful tools for teaching someone how to associate the loudness level, the actual sound they’re hearing. And it’s also great to take to loud restaurants and basketball games for fun if you are that way inclined to see what that noise exposure is when you’re out and about. But to get back to what one point you mentioned there, that the employer is responsible for a hearing conservation program. So, Laurie, as our regulatory person, can you tell us more about that?

Laurie Wells:

Sure. Now, of course, as we’ve discussed, regulations differ from one place to the next, and in some cases they even differ by the industry. For example, here in the US we have a different set of regulations that govern the general industry than we do for mining or for railroads or for the Department of Defense, for example. So, it’s really important for each employer to first know which regulations apply to their particular worksite, and then it’s good to recognize that there’s usually opportunities for employers to do more than just what the regulation specifies so they can go above and beyond the minimum in order to be more protective to workers.

Mohamed Saleem:

Even in Europe we see some differences between countries when it comes to regulations, but all of them have a basic requirement, to provide a comprehensive program that consists of multiple components. The parts that can be listed includes noise measurement, noise control, hearing protection, checking the hearing noise exposure of workers, providing training, and then the important element of record keeping, and finally, program evaluation.

Mark Reggers:

Just a few parts there for workplaces to consider. And look, it’s not easy for employees to manage all of those parts and people. Fortunately, there are specialists for almost every one of those components, like noise control engineers, audiometric technicians, and of course, occupational/industrial
hygienists as well.

Laurie Wells:

Right. And the record-keeping and the evaluation parts are really critical for the documentation, and also to be able to study those records to know whether or not a program is successful. At the end of the day, are we really protecting hearing or not, and how do we make continuous improvements so that we can be confident that the hearing conservation program is working? So, let’s talk more in depth about the hearing protection part of the hearing conservation program. So, hearing protectors reduce or attenuate the sound. Sal, would you talk a bit more about attenuation of hearing protection and how it’s measured?

Mohamed Saleem:

Sure. There are various standardized procedures to measure how much sound is reduced, or sometimes we call it “attenuation”, offered by the hearing protector. Now, this is done by testing a person’s hearing, firstly, without hearing protectors, and then, again, with hearing protection in place. Now, the difference in the hearing threshold between the two sets of tests show how much attenuation the hearing protector provides. The testing is done on a small group of people in a highly controlled acoustic laboratory setting. These attenuation data are then used to calculate a single
number that is presumed to represent how much attenuation a person will get when the hearing protection is used.

Laurie Wells:

Thanks, Sal. Yeah, I think it’s important for our listeners to know that these test conditions are very specific, and there are different criteria for testing in various parts of the world. For example, here in the US we tested specifically, and with that attenuation, we calculate what’s called the “noise reduction rating” or the NRR. I think many of our listeners are familiar with the NRR. But in other parts of the world they use different numbers. So, in the UK, you use the SNR, or the single number rating, and in Australia there’s even a different rating, the SLC80.

Mark Reggers:

So, you’re saying it’s possible to have the exact same product with different attenuation values, depending on where it’s sold because of the subtle differences in the test method and calculation?I know if I look at a box that we have locally here in Australia, we’ll see those couple of different numbers on the one box, on the different sides of the packaging.

Laurie Wells:

Exactly. So, again, going back to regulations, know what your regulations are, because it’ll specify typically which one of those systems you use, and you want to know what the attenuation rating is of the hearing protector. So, let’s talk a bit more about the different types. You mentioned earlier there’s lots of different types of hearing protectors to choose from. So, Sal, would you please describe for our listeners the different types that they might find out there on the shelf?

Mohamed Saleem:

Yeah, sure. We can think of hearing protectors in two broad categories, earplugs and earmuffs. In the earplugs category, there are disposable or sometimes called roll-down earplugs, the most widely used type of field protectors on the market. The soft form is rolled into a tiny cylinder, then inserted into the ear canal. Reusable earplugs, they are washable and flexible. Elastic flanges attached to a stem. There are other types called “push-to-fit”. These are soft form tips with a flexible stem. There is no need to roll the form tips before inserting into your ears. Earmuffs, plastic cups attached to an adjustable headband, cover the ears to help block out sound. Soft cushions seal against the side of wearer’s head. Then, we have banded soft form or elastic tips held in place by a flexible band. And there are electronic advanced human protectors, either in the form of earmuffs or earplugs, that have additional features that are really intended to improve the ability of someone to hear important sounds around them while still being protected from hazardous noise.

Mark Reggers:

So, Sal, the million dollar question I had for you, and I know it’s the one that have been asked many times, out of all these different types of hearing protectors, which one is the best one?

Mohamed Saleem:

That’s a good question, Mark. It all depends on what works for the individual user. There are many to choose from because all ears are different, and there are different situations, circumstances, where hearing protection is used.

Laurie Wells:

Great, Sal. And that’s a great spot to pause, actually, because we want to get into a longer discussion about how to select hearing protectors, and all the different factors that we need to consider when choosing them for our workers in specific workplaces. So, with that, thank you so much, Sal. We want to give you a heartfelt thank you, and really appreciate your time and energy and your expertise that you shared with us today.

Mohamed Saleem:

Thank you, Laurie, thank you, Mark. It’s been an absolute pleasure, and great fun to be part of this fantastic podcast. And I look forward to taking part in future events. Thank you, both.

Laurie Wells:

Well, Sal and Mark, this has been a lot of fun. I really like to close out by giving our listeners a challenge. So, you have some homework to do. What does your hearing do for you?

Mark Reggers:

Oh, homework. I’m nervous now, Laurie, but if I’m thinking about it, the very first thing that comes to mind, it lets us listen to this podcast. So, that’s a very important and exciting thing. And as a reminder to everyone, we will be coming back with the second part of our Hearing Protection episodes, where we’ll be looking at the hearing protector selection criteria. So, make sure you do do your homework as suggested by Laurie, and next time we will look into what can you do for your hearing. But thanks for listening to everyone. You can listen, subscribe to, and share this podcast through Apple Podcast, Spotify, Google Podcast, and most major podcast apps and platforms. If you have any questions, topic suggestions, or would like some assistance in your workplace when it comes to the appropriate selection use and maintenance of PPE, you can get in contact with this podcast by contacting your local 3M office, or visiting our website at mmm.com. This year we are celebrating the 50-year anniversary of the first NIOSH approved 3M filtering facepiece respirator and the 3M E-A-R classic ear plug. To all of our customers who have trusted the 3M brand PPE between now and then, we thank you. Around the world we aim to help everyone get the job done safely today, tomorrow and in the future. So, thanks for listening, everyone, and have a safe day.

Laurie Wells:

Stay safe out there, Mark.

Mark Reggers:

Stay healthy, Laurie. Thanks, everyone. See you next time.