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Summary of Noise Breakout Session Presentations and Discussion Submitted by: Lee Hager Plenary Presentation Summary Introduction Hager indicated that the group felt it important to integrate the discussion on a larger scale. It was impossible to discuss noise without addressing hearing and hearing health, and the discussion of hearing health was impossible to limit to the workplace without consideration of non-occupational exposure. The consensus of the group was that existing, proven technology exists and is readily available to control worker exposure to hazardous noise. Participants then focused on the underlying reasons for lack of implementation, the barriers to effective hearing loss prevention, and the research agenda necessary to promote the widespread application of these existing control and protective equipment technologies. Presenters The invited presentations provided a meaningful basis for discussion. Our presenters included: Noise Control: State of the Art and Unfinished Business Richard R. James Bob Bruce Tom Thunder Jon Weinstein Noise Control: Emerging Technologies Dan Johnson Richard R. James Hearing Protectors: State of the Art and Emerging Technologies Fredrick Lindgren Dan Gauger Kevin Michael John Franks State of the Art in Noise Control Significant technological progress has been made in noise control engineering, but real progress has been severely limited. The current regulatory regieme has resulted in limitation of effective control implementation to some industries, primarily larger facilities with top-down support of health and safety issues. Implementation has been limited in application and impact, with limited awareness of the availability of controls, especially in small and medium sized businesses. Consensus was that sufficient proven technology exists to control worker exposure to noise, both through noise control technology and techniques and through the use of hearing protection devices (HPD). Much of the discussion, then, centered on identifying the barriers to effective implementation of current technology. The group found it hard to present valid arguments on many salient issues due to lack of appropriate definitions.
We found that there is no feeling for the implications resulting from the unnecessary hearing loss that is accruing, both in economic terms as well as in social impact. We found no evidence that an infrastructure exists to support a noise control agenda were one to be created. There is no feeling for the essential training agenda. Who needs training – who are the target audiences? What do they need to be trained on – what are the important topics and what should be the emphasis of training? How do we assess the effectiveness of training? In summary, the existing hearing conservation paradigm has failed. Data to date show hearing loss is progressing at a higher rate than we would expect if existing programs were effective. We propose breaking the essential research agenda into a surveillance aspect, a new technology aspect, a personal protective equipment aspect, and a social marketing aspect. Surveillance Agenda Technical surveillance is required. We must revisit assumptions on scope of exposure. New information is required on the distribution of exposures. We must assess the current state of exposure monitoring. We propose a research agenda that will collect, collate and distribute data on noise exposure including:
We must assess the impact of changing workplace demographics on noise exposure distribution. The manufacturing base has changed significantly since previous studies were conducted. The fundamental responsibility and loyalty relationship between employer and employee has changed due in part to the effect of downsizing and outsourcing. We need to determine the effect of this dynamic on management of worker exposure to noise. Part of the technical surveillance effort should be the development and maintenance of a hazardous task inventory, or a compendium of industry specific noise hazards and noise sources. NIOSH has started this effort in the construction trades, but it should be expanded to cover all of industry. The other critical aspect of the surveillance agenda is economic surveillance. We have no feel at this time for the implications of current trend in hearing loss continuing. We must relate real costs to maintaining hearing health for the worker, for industry and for society in general. Hard costs include Worker’s Compensation; health care and the implications for hearing health maintenance under managed health care; and costs for hearing aids and rehabilitation. Indirect costs related to hearing health merit scrutiny as well. Research into increased risk of accidents due to impaired hearing, high noise levels, or compromised hearing due to use of HPD; productivity analysis; research on communication ability and related implications; and costs of under realization of career potential (example: US Army hearing requirements for promotion and retention) are important. In addition, analysis of worker expectation of retention and maintenance of full functionality needs analysis. Where our fathers expected to retire after 40 years in industry with compromised hearing, the current generation of workers with their focus on health and wellness will likely not be so accommodating. We need a national inventory of hearing critical jobs, both in the public and the private sectors. Part of this research should focus on methods for assessing auditory functionality; methods for determining the hearing-criticality of specific jobs, tasks, and occupations; and methods of accommodation to address workplace accessibility for the hearing impaired. New Technologies Distribution of information, specifically on controls, was one of the greatest needs identified by the group. We identified the need for a best practice compendium and an acoustical materials compendium to collect and distribute existing, proven control technology. Broad distribution of "buy quiet" specifications to aid the purchase of inherently quiet machines and equipment is another aspect of best practice information distribution. These steps can help integrate noise control with the business process. A national exposure database linked to noisy activities, hearing loss prevention outcomes, and hearing protection should be developed to provide a comprehensive reference. Research into the development of low cost personal noise dosimeters or personal exposure monitors with a retail cost of less than $100 (less than $20 is likely feasible) can make information about hazard levels and total noise burden available to large groups of exposed people, both on the job and off. Using the model of the musical greeting card, consideration should be given to developing an inexpensive hearing screening tool. While not clinical in precision, this kind of gross self screening could be a great asset in raising public awareness of noise as a hazard and in motivating the individual to maintain hearing health and function. Similar technology could be applied to personal hearing protector fitting. Analysis should be conducted on the effect of the redistribution of responsibilities for hearing health. Based on current business trends, we expect a shift from sole management responsibility under the hearing conservation paradigm. The new paradigm will entail greater worker involvement, as the worker bears more responsibility for their healthcare, and supplier involvement as they bear more partnership responsibility for ensuring that their industrial consumer maintains a safe and health workplace. Part of the supplier link involves consumer products as well. A labeling requirement like an MSDS for noise that would communicate to end-users the level of hazard, consequences of use, and appropriate self protective behaviors (like using hearing protection or limiting time of use) can close the gap between the linked exposures in the workplace and elsewhere. Personal Protective Equipment Important aspects of the HPD utilization issue merit research. We have no current definition of HPD comfort and no real definition of effectiveness. HPD fitting, or an assessment of the protection provided by given device under given conditions to a given individual, should be addressed with improved methods and technologies for field fit testing and user training. Simple but reliable methods for self-assessment of fit should be developed, with annual training and verification of appropriateness of HPD selection part of the hearing loss prevention process. Further study is needed on the effects of HPD on functionality in the workplace. Analysis of the effect of HPD use on warning signal detection; localization of noise sources; and speech and communication in the workplace are important. In addition, each of these research aspects should be considered for both the normal-hearing and for the hearing-impaired. New technologies integrating speech communication systems and other technologies with HPD should be pursued, with special focus on tailoring systems for hearing impaired. Integration of multiple technologies including chemical exposure monitoring and other health surveillance should be considered to increase value and raise the credibility of the use of these devices. Social Marketing One of the fundamental failures determined by the group was the sole reliance on regulation and on management for responsibility for hearing health in society. Lack of a broad based social marketing effort to raise the awareness of the public on hearing health as a wellness issue speaks to under-valuation of hearing health in society. The large-scale awareness campaign which will be required to raise awareness of society in general should be based on wellness models. This effort could be started by a consortium of professional associations to promote hearing health as wellness as a new paradigm. Worker groups, including organized labor; employers, both large and small; and the general population should be mobilized. A focus on youth, using anti-smoking or other public health awareness models, could be a great preventive measure to improve the hearing health of those entering the workforce. Noise awareness media should be developed using tools like the tinnitus demonstration tape employed by the Carpenters Union and hearing loss demonstration media.
Breakout Session I: State of the Art and Unfinished Business Richard R. James, James, Anderson & Associates, Inc. Current State of the Art The Bolt, Beranek, and Newman study of 1976 developed as background for the Hearing Conservation Amendment reflected expectations that, after "best effort" engineering controls, by 1985 less than 1% of the workforce would be exposed to noise greater than 90 dB(A) TWA, and that 3.6% would be exposed greater than 85 dB(A) TWA. One reason for the failure to achieve these goals is the current enforcement paradigm, under which employers were permitted to substitute hearing conservation efforts for noise control where TWA exposures did not exceed 100 dB(A) TWA, predicated on the assumption that both efforts would achieve equal effectiveness in worker protection. Evidence that this served as an excuse to abandon efforts to protect workers against the effects of noise is found in the cost analysis of effective HCP efforts and current market studies. 1976 cost analysis = $32 per worker to provide effective hearing conservation. 1983 Hearing Conservation Amendment cost analysis = $62.73 per worker 1992 DOL analysis = $86.60 per worker Thus, the market estimate for hearing conservation services in industry, using the NIOSH estimate of 30 million workers exposed to noise levels above 85 dB(A) TWA, is $1.9 billion even using the 1983 HCA analysis. We see no evidence of expenditures approaching this level in industry. A recent market analysis reflects projected market for hearing conservation services and products as follows: Hearing Protectors = $180 million Audiometric Exam = $120 million Market estimates for monitoring and noise control are so small as to be unmeasureable. Per the NOES study, little activity in protecting worker hearing is evident in industry.
We can only conclude that the noise control market is currently in suspended animation, and noise is a non-issue for most employers. Problems with current system There has been a failure in the exposure monitoring regime. There is no requirement for any systematic or documented procedure; no requirement for frequency of monitoring; and a failure to provide useful results for decision makers/management. Useful information for program management such as Hearing Conservation Program trends and Noise Control effectiveness measures has been absent. No correlation is made between hearing conservation effort and noise control effectiveness. Key interrelated data has been managed separately, under the charge of different functional group both locally at the plant level and globally at the corporate level. Exposure data, audiograms, worker demographics, Hearing Protection selection and use, and training records are collected, stored and managed separately with little or no correlation. Currently, equipment suppliers consider noise control optional. "Buy quiet" purchase specifications must be considered a "feasible engineering control" measure, and lack of a concerted and documented effort to obtain new equipment which will not add exposure risk to the workforce should be a citeable offense. This is increasingly important given the amount of non-occupational exposure in the workforce. "Buy quiet" purchase specifications share a number of common characteristics.
Summary: At present, there are significant gaps in the both research data and program implementation. We have no handle on:
Thomas Thunder, Acoustic Associates
False
Factors that have diminished the control of workplace noise Industry has, in large part, defaulted to reliance on hearing protection devices (HPD) in lieu of noise control. HPD was never intended as replacement for noise control. Where control technology has been applied, sound absorption has in many cases been viewed as a panacea. It is assumed that absorption is effective, when in many cases, this is simply not true. OSHA’s enforcement stance has been a barrier to effective control implementation. In most cases, fines have been too small to raise awareness. I suggest that we consider making fines commensurate with amount of overexposure, such that the greater the overexposure, the greater the penalty to the employer. Hearing loss formulas and Worker’s Compensation formulas undervalue hearing. For example, the average hearing loss claim in Illinois is $16,000 before expert witness and attorney fees. More than 12 formulas exist with great variability, resulting in confusion and lack of consistency. In addition, the political basis of worker’s compensation results in claim amounts and procedural hurdles to realistic compensation for hearing loss. We are seeing an interesting trend in litigation, however, where workers are pursuing compensation outside the exclusive remedy of worker’s comp by suing the manufacturers of noisy/hazardous equipment. The multiple criteria (85 dB(A) TWA action level vs 90 dB(A) TWA criterion level) are confusing to industry and should be revisited. The fundamental unfinished business in noise control, however, comes down to a lack of knowledge. Little is communicated in higher education or in industrial practice about the importance of source controls. There is a severe lack of academic training programs on noise control, and in fact, engineers are graduating with absolutely no noise knowledge or training. There is no infrastructure to support acoustic engineers. Robert D. Bruce, CSTI – Progress on Noise Control in the Workplace History of Noise and Hearing Issues Issues of noise exposure and hearing loss have a long history, starting with Pliny the Elder and his observation that people living near waterfalls with the attendant noise exposure developed hearing loss. Ramazini and the coppersmiths through observations related to boilermakers in the late 19th century and Holt in 1882 in the blacksmith, weaver, railroad worker trades indicate convincingly that we’ve known the effects of noise for over 100 years. What constitutes hazardous noise is another issue. The generally accepted criteria is that of 90 dB(A) TWA; upper limits vary significantly based on factors such as exchange rate. For example, the ACGIH criteria permits 28 seconds at 115 dB using a 3 dB exchange rate, while OSHA permits 15 minutes at 115 dB with a 5 dB exchange rate. Hearing protectors have a long history as well. HPD history reflects the effect of regulation in stimulating innovation. From 1880’s to 1920’s, for example, less than 20 patents per year were issued related to HPD. In the 1970’s and 1980’s, after the promulgation of regulation more than 70 patents per year were issued. Noise measurement history traces back through Lockheed measurements from the 1940’s (with resulting sound levels of 92 to 130 dB) and the WADC Technical Report. One of the first published analyses was in a 1953 AIHA Quarterly, titled Noise Surveys in Manufacturing Industries. Octave band measurements were taken in 600 locations and results compiled. Current state of noise control Who learns of noise controls/hearing loss issues? First, engineers, doctors, and scientists. Second, management; and third, workers. Due to this default system of information dissemination, the issue has historically not been treated seriously. The fundamentals of noise control are well understood, dating from the Noise in Industry publication in 1944. This document even included a seminal noise purchase specification. Several terms were employed in the past to describe the activity we are discussing. Everything from noise conditioning to noise reduction to noise control have found a place in the lexicon. Perhaps we should have called it Noise Prevention to give this issue he credibility it deserves. Technical feasibility as used today is based in large measure on the BBN Controls/OSHA report prepared in the context of the Hearing Conservation Amendment. It included a list of sources and controls found throughout manufacturing. One of the charges of the new defunct Office of Noise Abatement and Control involved product labels and information regarding hazardous noise. Labels were intended to provide worker warnings of hazard and consequences of use. Progress has been made In 1998, we have better materials for acoustical treatment and engineering controls and a better understanding of their use. We are seeing, however, a transfer in responsibility for noise control as a function of the current business trend toward downsizing, resulting in more subcontractors. Employers have outsourced health & safety responsibility to these subcontractors at the same time they are putting pressure on subcontractors to reduce costs. The net result is that the subcontractors use HPD as substitute for noise control. What do we need to do? Several research projects should be considered to address these needs.
Summary Engineering is the most trusted profession in America. This trust entails responsibility and a certain standard of excellence. As professional noise control engineers, we have the obligation to inform people about the potential hazards of excessive, unprotected exposure to noise. Jon Weinstein, Industrial Acoustics Corporation Source enclosure is a proven and feasible noise control measure. Proper design is key to success, with appropriate access designed into the enclosures. Enclosures are low tech, but effective with 20 to 30 dB reductions common. Basically, this is a mechanical engineering solution to the noise problem. Lots of things are feasible with good basic mechanical engineering and design. These examples (Mr. Weinstein showed a number of photographs of enclosure installations) are Primarily from mid-1970’s through early 1980’s, since the most recent emphasis has been on environmental issues rather than workplace exposure control. Receiver/personnel enclosures are another proven approach (examples provided). I can’t understand why expenditures are off the radar screen when these kinds of feasible controls are available. Absorption is a consideration where reduction of reverberant field will provide benefit. Gas flow silencers have also been proven effective in many situations. Group Discussion Banach: Two summary points: we’ve come a long way and what’s really changed? We are where we were 25 years ago, with some pockets of exception. We are twenty-five years in and the marketplace doesn’t have a clue. Anderson: How do we encourage engineering? What are the incentives? Compliance? James: We’re missing a role model for effectiveness. We must establish benchmarks and take corporate staffs "out of comfort zone" on this issue. Anderson: Can we use expenditures on HCP/HLP as a measure of commitment? Bruce: No, but what then motivates action? Bad press or publicity, but there is no danger of that in HC/occupational area. Daniel: How can we use that to our advantage? Thunder: We must find a way to use cost. Economic feasibility was driving factor for current status. We’re digging the same hole if we use reliance on economic factors. James: Could inspectors start to look at funds allocation/budgets for HCP/HLP? The CPL intended to balance engineering cost with HCP/HLP. If hearing loss exceeds presbycusis, inspectors should look at budget to see if program has minimal or sufficient financial support. Anderson: Use buy quiet to encourage engineering controls Brandys: NIOSH needs to get global perspective. There is success evident in the noise area in other areas and with our foreign competitors – Europe is an example. The reality of conditions in the US is that if it’s not in the regulation with significant enforcement penalties ($) it won’t happen. Bruce: Could we consider attaching fine to each recordable hearing loss? Use the OSHA 300 log as an enforcement tool. Brandys: That would encourage falsification of reports, underreporting of hearing loss, and fabricating data. I realize that this bears criminal penalty, but would industry consider the risk worth the reward? Daniel: We need small business focus. In many facilities, there is no current awareness of hazard. We’re dealing with language barriers (Spanish and Vietnamese at least) in the workforce, compounded by a lack of community/general public understanding of the issue of hazardous noise. Many of these small employers are marginal operations, and their number is increasing due to outsourcing. We must find a way to impact the community. Insurance carriers have been ineffective in pursuing this issue. Johnson: Look to Europe/EC as model to eliminate unfair competition Franks: ISO 9000 certification ostensibly carries over to suppliers, but is not enforced in H&S areas. Resnowski: Perhaps we need a multi pronged approach, including a best Practices compendium, involvement of manufacturers and designers, community and public relations efforts and training and education to make this work. Franks: Who could pay for this effort? OSHA? NIOSH? SBA? Hayden: NIOSH has recent history (asphalt machinery) of success with equipment manufacturers with just the threat of regulation. Bruce: No one understands the impact of hearing loss. Schneider: One of the fundamental issues is that, as a society, we undervalue hearing. My firm recently offered fully paid for hearing aids to 69 candidates, based on their audiograms; ten took advantage of the offer. Thunder: Hearing aids carry stigma. I see a similar stigma with requiring people to use HPD @ 85 w/STS. Hayden: Worker’s Compensation is a non-issue nationally. Daniel: What about kids entering the workforce? Franks: NIOSH has had real difficulty recruiting "normal hearing" young test subjects for HPD research in Cincinnati – we’re having trouble finding 20 year old kids with normal hearing. Based on NIOSH estimates of hearing loss, Worker’s Compensation should be $10B annually; in 1986, the actual amount was $600M. Meyers: This is in part a generational issue. To our parents’ generation, hearing loss was considered part of the job. We need to move to or develop a model of "you take hearing, you pay". Weinstein: Noise control was a much easier sell in 1975-1980. The technology is there; interest is not. We’re finding more success in environmental applications than occupational. Thunder: Is this, or should it be, a lifestyle issue with retirees? Fechter: There are fundamental problems and perceptions when dealing with this issue. Hearing loss is insidious; it has a long onset; it’s non-life threatening; and there is a real perception that hearing loss is inevitable with age. Hearing aids are not well accepted. We are seeing, though, some good activity from organized labor. James: We need to turn the paradigm from hearing loss to hearing health. We must establish the cost to society if this trend is unabated. Banach summarized discussion for the group.
Breakout Session II: Emerging Technologies Dan Johnson – Instrumentation for the 21st Century The current state of the art in noise instrumentation is quite encouraging. Dosimeters with statistical output, smart sound level meters (SLM), real time analyzer (RTA) technology, and computer interfaces have made the job of noise measurement and exposure assessment easier. There are, however, deficiencies in the currently available instrumentation. For example, infra- and ultra-sound are not effectively managed currently. Impulses greater than 140 dB are difficult to manage. The wearer’s voice continues to be an issue when using dosimeters. While greatly streamlined from previous generations, the measurement equipment is still too bulky. Long term measurement remains difficult. Current instrumentation does not integrate automatic quality control, and perhaps most importantly, the instruments provide insufficient feedback to wearer. There are several issues that can and should be addressed in the near future. In the slightly more distant future, other technological advances should provide even better tools for exposure assessment. In the most distant future, noise analysis could be related to individual susceptibility. As we find ways to look at individuals and how they react to noise exposure from different types of sources, variable analysis could personalize noise exposure risk with an expert computer system built into the dosimeter. Conclusion Improvement is happening now, with the promise of great things to come in the instrumentation arena. Richard James: Changing Paradigm, Re-engineer the Process The elements of an effective hearing loss prevention process as laid out in the NIOSH Practical Guide for Preventing Occupational Hearing Loss are a good starting point for the discussion about re-engineering the hearing health maintenance process. To effectively change the paradigm, hearing health must be viewed as an asset, both by the individual and by the business community. To help this process and give it credibility, we need to develop an economic analysis of hearing health and implications, tying dollar values to both the direct and indirect costs of unnecessary hearing loss. There are safety issues involved with hearing health; no real measure has ever been taken of the accident related implications of hearing health, hearing loss, or use of hearing protection. The most compelling arguments, though, may be societal in nature. Who will bear the eventual long-term cost of hearing health for our generation? Most likely, this burden will fall on the federal government through the Medicare program. Thus, bad actors or poor hearing health managers will outsource their responsibility to taxpayers. To be effective, we must change the equation such that our perception is not that hearing loss prevention equates with compliance, but that instead hearing loss prevention equate with wellness. Hearing health is a wellness issue. Task-based exposure assessment modeling (T-BEAM) is an emerging technology that could help in this effort. The systematic collection of task related sound levels can be a powerful tool in communicating risk to those who can take the "on the ground" action to protect against the effect of noise – the worker. Constituencies Effective campaigns, like the one necessary for this paradigm shift, require a champion to carry the issue forward. Who are our constituencies, and who are the potential champions for hearing loss prevention?
Conclusion We need methods to put the pieces together. At the core, we must develop ways to identify, protect, and motivate the "at-risk" worker. We must direct and manage both hearing loss prevention efforts and noise control as business processes by communicating with the business world in the language they understand – money. Incorporating the fundamental noise control elements of buy it quiet (firm commitment to low noise purchase specifications for new equipment), make it quiet (retrofit noise control where appropriate) and keep it quiet (motivating workers and training maintenance staffs to ensure that noise controls are maintained), combined with the development of hard costs for both effective and ineffective hearing health asset management will enable real progress. Discussion:Daniel: No good methods are in use for noise studies meeting these criteria. Brandys: How do we deal with exposure dominated by single frequency, but where A-weighted exposures are below OSHA standard? This relates to hearing loss at specific frequencies. The EPA regulations cover this in the community arena and as nuisance noises, but is not well covered under OSHA. In addition, we need to clarify the effect of longer workdays – there is confusion under current regulation. Bruce: Can we find an industrial or business perspective on these issues? Daniel: I’ve heard of some good work from ALCOA in this area. Is that a potential model? Franks: We need a universal database – the Pan European effort may be a model. They looked at 10 noise areas and include consequences of hearing loss. Part of this effort was a session on measurement issues. One important aspect is to harmonize NoiseScan (the European effort) and Hearsaf 2000. We are changing the function of audiometry away from a recordkeeping effort to a worker functionality assessment and intervention tool. Brandys: We must publicize successes. Franks: The cheap dosimeter is a great concept. How can we convince instrument manufacturers, the business world, and the public of the utility of devices like this? Banach: Public awareness could be a key. Have we addressed hunters, fishermen with the message "what are you missing?" with hearing loss? Fechter: Risk communication is the underlying concept. Rosnowski: Can we use a web page? Bruce: The current OHSA CPL with100 dB default criteria for engineering must go. Palmer: Hearing aid rehabilitation and acclimation could be very effective. In my personal experience, the military paid for a full week at Walter Reed to ensure that I understood how to use my hearing aids and could use them effectively. They included my spouse; that support was critical in my acceptance of my aids. I believe they have done a study about hearing aid acceptance with and without acclimation and rehabilitation. Thunder: Insurers are asking for quantitative quality of life improvement analysis for insurance payment or hearing aids. Burks: Should we engage in dialog with "other side"? Franks: It appears that we’re all on the same side. If we’re going to "preach to the choir", our goal should be to increase the "size of the choir". We must learn to express hearing health in corporate language, and speak in and distill our issues to dollars. Schneider: In my company, a worker nearly fired due to hearing loss. He misunderstood verbal instructions, which led to errors in job performance, and nearly cost him his job and the company an experienced worker. James: Safety issues could have some significance in communication with the business community. The recent study in the Journal of the American Medical Association which correlated "disabilities" which, in this case, included self-diagnosed hearing loss, and industrial accidents was quite compelling. In addition, the Dutch Shipyard study in the mid-1980’s showed a stringer correlation between accidents and hearing loss/high noise that between accidents and drug or alcohol use on the job. I suggest a research proposal that would report non-occupational accident correlation to lost workdays, perhaps using emergency room data, that would measure increased likelihood of accidents due to compromised hearing health. Could we look at the correlation between high noise and compromised respirator use? Workers often remove respirators and hearing protection short-term removal to aid verbal communication. Bohl: John Casali has done some analysis on the FWHA truck driver criteria in a similar area. Bruce: In the 70’s, there was a study done at the Rayethon plant in Massachusetts correlating noise and accidents. One of the interesting findings was that noise control resulted in a reduction in absenteeism. Daniel: How do we disseminate this data? Franks: We need research in information dissemination. Rosnowski: Use common TTS measures like the radio test – if the radio seems too loud when you get in your car the next morning, you were likely overexposed the previous day. Thunder: Can we develop improved self-screening technologies, like the Audio-D Card with test tones or the Beltone piece with words? There have been speech intelligibility studies done in SCBA for firefighters if that could help. Breakout Session III: Personal Protective Equipment/Hearing Protectors Fredrick Lindgren, Peltor/Aearo Company: HPD Issues for the 21st Century Noise-induced hearing loss (NIHL) is the most common occupational injury. With the proliferation of hearing protection, how can this be? Selection habits could be a mitigating factor. While the Noise Reduction Rating (NRR) factors on current protectors range from 6 to 33 dB, most protectors exceed 25 dB, making them suitable for population at risk of exposure 100-115 dB. Evidence indicates that 95% of exposures are 95 dB or less, requiring less than 15 dB protection. At this level, nearly any HPD will provide sufficient protection, so why is HPD not preventing NIHL? Several issues come into play.
The HPD rating system may be a contributing factor as well. The NIOSH long method is a good measure, but relating that to the NRR, which is A-scale based, is subject to problems with low frequency dominance. The HML method is frequency specific and uses a dBA – dBC calculation to better estimate effectiveness in some environments. Buying patterns complicate the issue. End users have no control over HPD purchasing decisions in most cases, and buyers don’t consider comfort when making selections. NRR and cost are only factors typically considered when making these decisions. I offer these recommendations for selection. Where the TWA is less than 100, any HPD will do. Selection should be based on comfort and utilization. Where the TWA exposures approach 95, select carefully since with high exposures, appropriate selection is increasingly critical. Roadmap for 21st Century We need to develop realistic attenuation values. We should retire single number methods of assessing attenuation, and use the HML method where selection is critical. In place of the NRR, we need to develop single number method for rating HPD comfort. This will force comfort as R&D issue for HPD manufacturers. We need standards for non-linear HPD, like active noise reduction (ANR) hearing protectors and those offering sound restoration. We should evaluate the impact on of HPD on speech communication, and provide guidelines on using communication equipment in noisy environments. Dan Gauger, Bose Corporation: Hearing Protectors and Active Noise Reduction Overview of Active Technology While the application of active noise reduction (ANR) technology may have been oversold in some situations, especially in industry, the concept dates to 1930’s. It became practical in 1970’s with technological development in op-amps and miniaturized computers. The first commercial product was developed for general aviation application in 1989. The current uses of ANR technology in hearing protection include general aviation, military communication headsets (primarily in heavy armored vehicles), consumer products like those offered by NCT, Koss, and Sony, and some limited industrial applications. We must address some hard realities when discussing ANR in hearing protection applications. The cost, of course, far exceeds foam earplugs. ANR requires power, and there are technical issues (the "big woofer" problem and difficulty in pushing ANR frequency range) which are barriers to widespread application. ANR is not a panacea, and at worst is a placebo. Attenuation Measurement Issues How much attenuation is offered by ANR hearing protectors? The real-ear at threshold test (REAT) can’t be applied due to the electronic noise floor inherent in ANR devices. The microphone in real ear (MIRE) test is typically used, but these methods provide different values for passive devices at low frequencies. For example, the REAT exceeds MIRE test results by 7 dB at 125 Hz, and by 2 dB @ 250 Hz. What is the maximum SPL at which ANR works or provides sufficient protection? ANSI working group S12/WG39 is working on standard to address these issues. Attenuation, however, is not the only issue. It is critical to motivate the worker to use HPD; can ANR improve acceptance? ANR adds a degree of freedom to HPD design, and permits a reduction in band pressure, increasing comfort in some situations. This has been very important in the general aviation market. Could ANR increase situational awareness in areas such as conversation, machine noises, warnings, and alarms? HPD use is a safety issue, and ANR technology has the potential to be a benefit in this area. ANR sounds different to the user as well due to flatter response. Different earcanal occlusion effects could be a factor. Summary: ANR is a proven technology, but is a tough sell to industry. There are important questions yet to be resolved, including the benefit of increased worker acceptance; improved situational awareness; improved safety, and improved user comfort all speak to the underlying issue - what’s the added value in ANR technology? Kevin Michael, Michael & Associates, Inc.: Comprehensive Use of Hearing Protectors: Integration of Training, Field Monitoring, Communication, and Documentation Where do hearing protectors fit in the world of currently available HC services? The noise control programs have no consideration of HPD use; the hearing testing program has no consideration of HPD use; and the HPD manufacturers have concern only for highest NRR. There is little emphasis on HPD management, little support for OHCs on HPD selection, and scattered support for training & motivation on HPD application. ANSI working groups are looking at some aspects of HPD management to address some of these issues. Working Group S12/WG35 is trying to standardize a method for HPD selection to maximize communication ability in specific noise environments, and Working Group S12/WG11 is developing lab methods to estimate HPD field effectiveness; standardizing rating systems; and standardizing field monitoring systems to assess individual HPD fit. There are some field monitoring systems currently available and in use. FitCheck is used for insert HPD like earplugs. It replicates the lab procedure under headphones and provides objective measurement of HPD attenuation on individual user. It has been field tested at ALCOA Cleveland and Lebanon, PA; Latrobe Steel; Alyeska Pipeline; and with the US Army. Spectrum is a important factor in HPD effectiveness. An earmuff with an NRR of 24 was tested under varying spectral conditions. It showed a field test NRR of 24 dB protection in a flat spectrum; 35 dB in a rising spectrum (High frequency intensive); and 8 dB in a falling spectrum (Low frequency intensive). A dual microphone system is available for testing earmuffs. The European Union has developed guidelines for sound levels under hearing protectors to maximize communication ability (EN 458). Using octave band analysis, calculate A-weighted sound level under protector. These are the EN458 acceptable limits.
Maximizing communication while using HPD encourages full shift use and discourages the "more is better" assumptions underlying HPD purchasing in industry. In addition, it provides a basis and incentive for manufacturers to develop wide range of comfortable, moderate attenuation HPD. John Franks, NIOSH: Carpenter Training Video Discussion: Thunder: Is the 7dB C to A correction used in NRR calculations based on NIOSH studies of typical industrial spectra? Franks: We find it to be more inclusive than using C alone. Lindgren: A 5 dB correction may be better, but any single correction factor will be wrong. Meyers: We’ve received many calls on OSHA’s 50% derating scheme; we feel it leads to overprotection with proper HPD use. Johnson: Where did "95% exposures <95 dB" come from? Franks: From the BBN study in the 1970’s. Daniel: How can we assess the effect of a video like this without audiometric exams? Franks: We use worker observation and questionnaire techniques, which have proven quite effective. Unknown: I have questions about the intermittency correction factor; should we use a 5 dB exchange to 100 dB and 3dB above that? Lindgren: Yes, we should vary exchange rate by level Anderson: For Kevin Michael – Was the ALCOA fit test used for research or for training/motivation of the workers? Michael: It was actually used for both. We tested from 250 to 2k; the test took 5 to 7 minutes. Currently, the test equipment costs about $3k, but that’s building single units. It’s possible to build this kind of test into the audiometer as well. Daniel: How much of the world does NONE of this? Bruce: For Dan Johnson – I see great potential in your technology ideas. Could we tie the HPD in with hard hat and throat mic for communication? Build two-way radios, other biological monitoring, and, "man down" warning systems into the unit to add value. Gauger: Similar ideas are under consideration now. Meyers: For Michael – Did you test repeatability and consistency in fit testing day to day? Michael: No | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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