When OSHA defined the components of an occupational hearing conservation program in 1983, it heavily relied upon annual audiometric testing and training to be the major tools in preventing noise-induced hearing loss (NIHL) in the workplace. Even well-intentioned safety managers who implement the program often are met with a surprising outcome after their efforts: continued hearing loss, as measured either by audiometric shifts in hearing or by rising compensation claims.
The causes for continued occupational hearing loss are not easily solved by just another audiogram or training class. Many employees, for example, incur noise-induced hearing loss due to off-the-job exposures, yet are identified only through on-the-job audiometric testing. As a result, the hearing loss is attributed to the job. Additionally, the cycle of annual audiograms is notoriously slow in identifying problems.
Once an employee is identified as having a shift in hearing, it easily can take years before you can determine whether the intervention plan (retraining and refitting of hearing protectors) was successful. It is not uncommon to find repetitive hearing shifts among noise-exposed workers; a sign of an audiometric testing program that merely serves to document – not prevent – hearing loss.
But a growing body of research points to another culprit in ongoing hearing loss: the group effect. When hearing protection is chosen based upon the published group noise reduction ratings (NRR), protection levels decline. When training is offered in large groups rather than at individual or small-group level, effectiveness declines significantly. And when noise exposures are measured for broad groups of workers in a noisy setting, the value of the monitoring declines.
The three companies profiled in this article offer bold strategies that go beyond an OSHA-standard hearing conservation program, and personalize their hearing protection efforts to the worker. The return on their investment is a significant decline in the measurable hearing loss and/or compensation claims, and in some cases, a measurable stop in progression of hearing loss.
One-on-One Training
One California manufacturer reported a sea-change in their hearing conservation efforts when they personalized their training. While some content in the OSHA-required training can be covered in a class, two critical parts of the training are best covered individually: the audiometric results, and how to fit the hearing protectors.
To bring the point home about hearing conservation, this employer unplugged the video training that repeatedly had been shown for 12 years, and instead invested just a few minutes in one-on-one training with each worker.
“It was an eye-opening experience to watch as employees who had sat through years of group training couldn’t demonstrate a proper earplug fit in the one-on-one session,” the safety supervisor remarked. “We set aside the video and made a new training rule: one-on-one training, and no employee leaves until they can demonstrate a proper fit of the earplug.”
Many companies find there is no better time for that one-on-one training than immediately following the audiogram. The worker is focused on hearing, anxious to know results and more compliant in changing behavior.
Companies who delay that fit training until a group of employees is assembled unknowingly drop one their most powerful tools against noise-induced hearing loss. A 3-year study at a large utility company1 showed that the rates of significant decline in hearing were twice as high in a group that received no feedback following audiometric testing, compared to their counterparts who received immediate feedback and one-on-one training following the audiogram.
That “how to fit an earplug” training might be a simple, 1-minute demonstration. In a study of 192 noise-exposed workers at a steel mill, employees who received a very brief personal tutorial on how to properly insert the earplugs achieved, on average, 14 decibels (dBA) more protection from their earplugs than prior to instruction.2
Fit-Testing
In a conventional hearing conservation program, decisions about hearing protection are based upon the NRR on the package. But how likely will an individual worker achieve the NRR on the package in daily use? “Unlikely” is the resounding answer from scores of studies over the past decade.
Fit-testing systems are available that allow employers to measure the attenuation of any earplug. The result is a number called the personal attenuation rating (PAR), which is the protection level of that particular earplug worn by that particular worker. Fit testing provides instant feedback whether a worker has a correct fit, and can assist in immediately identifying and re-training those workers with a poor fit. Fit testing also can be used to assist employers in selecting the right hearing protector for each employee from a variety of suitable choices. Armed with individual fit test results, the population-based NRR becomes irrelevant in determining whether a worker is protected from hazardous noise.
Committed to reducing its long-standing rate of hearing shifts in its audiometric testing, one large, multi-site manufacturer instituted fit testing on over 1,500 production workers over multiple years. For their initial test, employees were asked to use their usual earplugs (the ones they wear each day in production) and fit them in the usual manner with no help from the training team. Not surprisingly, 45 percent of the workers did not meet the minimum protection criterion set by the company (at least 15 dBA of protection in both ears), despite their participation in the company’s long-standing hearing conservation program. Those employees who did not pass the criterion on their first test received one-on-one fit training, and in many cases, alternate earplugs were tried. The employees were then retested.
After individual fit training, retests confirmed the dramatic effect. Employees improved an average of 13 dBA in their protection levels, increasing average protection by 120 percent as a group. In a post-test survey, 84 percent of employees stated they were better able to fit their earplugs. And the comment cards included many personal testimonials:
“I learned I’ve been using my earplugs wrong my whole career.” “Just learned how to effectively roll the plug before insert.” “I’ll put a little more effort and get ’em deeper!” “Amazed at difference with proper fit.”
The benefits of fit testing recently were highlighted in a best practices bulletin published by an alliance of OSHA, NIOSH and National Hearing Conservation Association (NHCA). The document (available for download from the alliance Web site3) endorses fit testing as a best practice in a hearing conservation program because it provides improved employee training, allows for refitting of workers demonstrating a threshold shift and acts as a critical tool in selecting the best hearing protector for each worker.
In-Ear Dosimetry
For one large smelter in the northwest, the OSHA-standard hearing conservation program wasn’t stopping hearing loss. “We have 25 years of audiometric data to prove that our hearing conservation efforts weren’t working. We’ve simply documented the progression of hearing loss in our hearing conservation program,” the corporate industrial hygiene manager lamented.
Despite all the components of a regulatory-compliant program in place, the liability for occupational hearing loss rose steadily year after year. When risk managers noted the dollar value of the pending liability, a summit was called to re-think the program.
What came next far exceeded regulatory requirements. Instead of defining a worker’s noise exposure with shoulder-mounted dosimeters, the bar was raised. Now, noise exposure at each worker’s eardrum was defined as the bottom-line measure of exposures, using in-ear dosimeters. Ambient noise monitoring answers the question: How much noise is around this worker? In-ear dosimetry, meanwhile, takes into consideration how effectively the hearing protectors are working. Simply stated, in-ear dosimeters answer the question: How much noise is reaching the eardrum? This is the only metric with direct potential to measure and prevent further progression of hearing loss.
Unlike conventional noise dosimeters, in-ear dosimetry uses a microphone pick-up placed under the earplug (via a thru-hole) or under the earmuff (wired inside the earcup). This in-ear microphone placement measures the noise levels actually reaching the eardrum under the protectors. At the end of a work shift, when the dosimeter is placed in a reader, the composite noise dose tells whether the worker properly has worn the protectors. An added benefit of in-ear dosimetry is its ability to monitor the effect of “cheating” on the overall noise dose, those few minutes here or there throughout the work day when the workers removes the protectors for just a few minutes in order to facilitate conversation or comfort. In these situations, the in-ear dosimeter, now exposed to ambient noise unprotected by the earplug or earmuff, generates a high noise dose.
The results from fitting high-noise-exposed employees with in-ear dosimeters was impressive. Analysis published by researchers at the Yale University School of Medicine confirmed no further progression of high-frequency hearing loss among the 78 noise-exposed workers.4 Also, those who participated in the in-ear dosimetry program demonstrated significantly better protection than a control group of 234 workers, matched for age, duration of employment, initial hearing level and similar noise levels in the facility.
One side benefit of the in-ear dosimetry program was documented differentiation between on-the-job and off-the-job noise exposures. With in-ear dose measurements showing low exposures under well-fit protectors, the employer has solid documentation that a noise-induced hearing loss, if it occurs, was not due to workplace noise. Other causes then can be explored, such as off-the-job hobbies or medical pathologies.
By shifting their hearing conservation efforts away from ineffective group methods toward individual training, these three employers successfully reduced their rates of – and liability for – noise-induced hearing loss. One-on-one training, personal fit-testing and in-ear dosimetry have been documented to reduce, and in some cases, eliminate work-related hearing loss. But the benefits of this personal approach certainly extend beyond the workplace, as employees apply their newly learned healthy hearing habits both on and off the job.
Brad Witt is the director of hearing conservation at Howard Leight/Honeywell Safety Products (http://www.howardleight.com). He has a B.S. in communication disorders from Brigham Young University and an M.A. in audiology from Northwestern University. For 14 years, he managed a hearing conservation practice in California, providing OSHA-standard services at 175 locations. He has served as president of the National Hearing Conservation Association (NHCA) and has presented more than 200 hearing conservation seminars on behalf of Honeywell Safety Products over the past 6 years in 15 countries. He can be contacted by email at [email protected].
References
1 Witt, B., “Immediate Feedback in a Hearing Conservation Program.” Presented at National Hearing Conservation Association, 1992.
2 Michael, K. and C. Bloyer, “Hearing Protector Measurement on the End User: A Case Study.” Presented at National Hearing Conservation Association, Feb 1993
3 OSHA Alliance Best Practices Bulletin available at http://ohp.nasa.gov/topics/hear-cons/osha_alliance/AllianceRecommendationForFitTesting_Final.pdf
4 Rabinowitz PM, et al. “Effect of daily noise exposure monitoring on annual rates of hearing loss in industrial workers.” Occupational and Environmental Medicine, published online Dec. 30, 2010.