Interview with Elliott Berger M.S., Senior Scientist for Auditory Research at E A R / Aearo Company, Editor of the Council for Accreditation in Occupational Hearing Conservation's (CAOHC) Hearing Conservation Manual, 4th Edition
Beck: Elliott, thanks for joining me today. You're well known for your work in hearing protection and conservation, as well as for your efforts in the broader area of noise management, but before we get to that, would you please tell me a little about your educational and professional history?
Berger: Hi Doug. I studied physics and earned my undergraduate degree at Renssalear Polytechnic Institute. Following that, I went to North Carolina State University and was fortunate to receive funding for a NASA study addressing the effects of noise on sleep while earning my master's degree. After that, I focused on the effects of occupational noise exposure on hearing loss. My master's degree was from the mechanical engineering department, with a major in acoustics, and that was back in 1976.
Beck: What about your first professional position after graduating?
Berger: I started with E A R, which at that time was a small subsidiary of Cabot Corporation. They were looking for an acoustical engineer to do noise control and damping work. They actually were looking for someone with a PhD, and although I didn't have one, I applied and hit it off fantastically well with the Technical Director, Ross Gardner, Jr., the fellow who invented the E A R® foam earplug. He thought I was perfect for the job, and I thought it was a great position at a wonderful company, and so I joined. About 6 months later I switched my focus from noise control to hearing protection, and I've been doing that now for the company for 27 years. I've been able to conduct research and set-up a lab, become involved with numerous professional organizations and committees, and produce an extensive list of publications - so it has been a fabulous opportunity.
Beck: I know you've been very involved in your profession, for example; you're the past-president of the National Hearing Conservation Association, you were the Chair of the American Industrial Hygiene Association (AIHA) Committee on Noise, you're currently the AIHA representative to the Council for Accreditation in Occupational Hearing Conservation (CAOHC), and you Chair the American National Standards Institute (ANSI) working group for the Standards on Hearing Protection. Elliott, regarding the ANSI standard for measuring hearing protector attenuation, when was it written?
Berger: Good question. It was promulgated in 1997 and then reaffirmed, as is, in 2002. Our ANSI working group, the one responsible for that standard, is now working on ratings for hearing protectors. One piece of the hearing-protector pie that's missing is that there is no ANSI standard for number ratings of hearing protection devices (HPDs). Despite the fact that everyone knows about the Noise Reduction Rating (NRR) an ANSI standard specifying how to compute that number is lacking, although it is enshrined in an EPA regulation. So we're determined to evaluate, modify, and standardize the protocol, which I think that will be useful for the professional community.
Beck: I agree. If I may, I'd like to change topics to the book I have in front of me, written by Alice H. Suter Ph.D., titled The Hearing Conservation Manual, 4th Edition, which you edited and is available on the web at: www.caohc.org/manual.html. I'd like you to spend a moment or two addressing; Who is CAOHC, and why did you guys assemble this text?
Berger: Sure, Doug. Yes, I had the pleasure of editing the book, which was written by Dr. Alice H. Suter. CAOHC originated when four professional societies got together in the 1950s to teach nurses how to screen for hearing problems. That group assembled a document called the "Guide for Training Audiometric Technicians in Industry" which was adopted in 1965. There has been an surge in knowledge since that time, and today, CAOHC has representatives from each of the following groups; American Academy of Otolaryngology, American Association of Occupational Health Nurses, American College of Occupational and Environmental Medicine, American Industrial Hygiene Association, American Society of Safety Engineers, American Academy of Audiology, American Speech-Language-Hearing Association, Institute of Noise Control Engineering and the Military Audiology Association. The main goal of CAOHC involves training and certification of Occupational Hearing Conservationists (OHCs). The OHC is the person who conducts the pure tone audiometric testing in an occupational hearing conservation program, under appropriate supervision. The OHC takes 20 hours of instruction and must pass an exam. The Hearing Conservation Manual is a text that describes the body of knowledge with which the OHC must be familiar to perform their function. The book forms the basis for the curriculum taught in the OHC training courses. There are about 22,000 OHCs in the USA today.
Beck: Elliott, I'm glad you mentioned that. The book is not just about noise and hearing loss, but is much more. It includes occupational hearing conservationists (their mission, training and role), the effects of noise and hearing conservation, anatomy and physiology of the ear, hearing disorders, introduction to sound, and then all manner of standards and regulations pertaining to OSHA and mining, military guidelines, CAOHC audiometric testing guidelines, audiogram interpretation, noise measurement and control, an entire section on hearing protection devices (HPDs) and training and motivation for the employees in noise and wearing HPDs, and finally recordkeeping.
Elliott, I wonder if you, as someone who has studied and focused on noise-induced hearing loss, can give me any estimates as to the numbers of people at risk for hearing loss due to noise exposure, secondary to their employment?
Berger: Well, the numbers and estimates vary substantially from source to source, and there's no one gold standard that everyone agrees to. NIOSH in their 1996 publication suggested that 30 million workers in the USA are exposed to damaging noise. But then oddly enough, in 1998, they used the number 5 million. Of course, not only do the population estimates vary, but as you know Doug, the NIOSH and the OSHA definitions of dangerous levels vary too, and so we have variability in the definitions, the quantities of people, and the survey techniques. My best guess is that the "true" number of people at risk in the USA is upwards of 10 million.
Beck: Thanks Elliott. I'd like to also mention that one other part of your life at E A R has been spent compiling and publishing the EARLog series...which I used extensively when I was studying at the University of Florida, and I like to recommend that fine body of work as the foundation upon which so much of the noise control and HPD issues are centered. The whole series, some 21 reports and monographs are available on the Internet at www.e-a-r.com/hearingconservation/earlog_main.cfm, and again, they are an amazing resource.
Berger: Thanks Doug. I appreciate that.
Beck: Another thing I'm interested in is hyperacusis in children, and how difficult it is to diagnose that because children are not usually competent at detailing their history! You and I were speaking earlier in the day about hyperacusis and you mentioned you were familiar with an automobile airbag deployment in which the SPL reached 175 dB ... which is truly unimaginable to me....but I believe hyperacusis has a relationship to noise induced hearing loss, and particularly to traumatic noise exposure, such as a shotgun blasts, an airbag deployments, firecrackers etc?
Berger: Yes, I think so. There is little objective data in the hyperacusis literature, and probably even less as it relates directly to children, but you're right, there does appear to be a strong relationship between traumatic noise exposure and hyperacusis.
Beck: If you don't mind, would you tell the story about the airbag deployment to which I just referred?
Berger: Sure Doug. Impulsive or blast type sounds certainly can be related to hyperacusis and I have been looking into related topics for the last two years or so, and some of the studies involve airbag deployment. There was a important and troubling case involving a woman and her husband, who were in a car accident. Both airbags deployed, needlessly, I might add, since this accident was a side impact. Her husband was fine, but she had immediate onset of aural fullness, hyperacusis and tinnitus. It has gone on for some ten years now. When she washes the dishes she has to wear HPDs, and she is unable to leave the house without hearing protection on, she cannot spend time with her grandchildren ... and in many respects, she is disabled by hyperacusis, secondary to air-bag deployment, and it has totally affected the quality of her life.
Beck: Elliott, I could ask you questions all day, but let me just mention one other somewhat related topic, which is amazing to me, and which you have thoroughly investigated and is detailed in the Hearing Conservation Manual...and that is the lack of a relationship between the NRR numbers printed on the HPDs, and the "real word" attenuation provided.
Berger: Yes, Doug, that's a very real problem, and one that my ANSI working group addressed in the development of the Method-B procedure in the current hearing protection standard (ANSI S12.6-1997), and one that we are continuing to investigate. In essence, when we actually measured the "real world" noise attenuation of many HPDs, we found that the "real world" numbers were almost always a small fraction of the NRR. Of course, this was very frustrating for many of us, but a very important finding. There have been 30 some studies since the mid 1970s that have looked at this, and the lack of a relationship between the NRR and the true attenuation in the field is a significant and well known problem.
Beck: The graph that you assembled, which details these findings can be found as Figure 10-20 on page 113 of the 4th edition of the Hearing Conservation Manual. I would like to urge all hearing healthcare professionals to review this information...it is startling, important, and impacts our day-to-day management of patients at risk for noise induced hearing loss.
Elliott, I'd like to just mention the other book, The Noise Manual, 5th Edition which is the text from the American Industrial Hygiene Association manual, for which you were also the principal editor as well as author for a number of chapters. Can you tell me a little about that one too?
Berger: Yes. I've been involved with the last two (4th and 5th) editions of that text, which first appeared in 1958. The current edition is copyrighted 2000. It is some 800 pages in length and is the standard text in the hearing conservation community.
Beck: I know we don't have enough time left to really outline and review that text, but I would note that the Noise Manual is more in-depth, and is perhaps more appropriate for audiology and noise control engineers. In other words, the Noise Manual is more detailed and more comprehensive, and can be obtained via the AIHA www.aiha.org/webapps/commerce/product.aspx?id=ENOM03-619&cat=&subcat=. Thanks so much for your time and talent Elliott! I always learn a lot working with you.
Berger: Thank you too, Doug. This has been an enjoyable conversation for me as well.
For more information, please visit the following websites....
Hearing Conservation Education Website
(manufacturer of hearing protection and other safety products)
National Hearing Conservation