Occupational Health & Safety

NHCA Conference Highlights Top Hearing Conservation Trends

A researcher from West Virginia University proposed a battery of audiologic tests that could help to diagnose solvent-induced hearing loss.

When some people think of hearing conservation, they limit their thinking to hearing tests and hearing protection. That's a mistake: Hearing conservation is so much more. When it's most successful, hearing conservation is an integral element of an enduring and nurturing culture of safety that's focused on proven processes to prevent accidents and injuries.

The National Hearing Conservation Association (NHCA) is the one professional association dedicated to hearing loss prevention in all aspects of society. For those trying to improve their hearing conservation programs, NHCA is a great resource. Each year, hearing conservation managers join safety directors, audiologists, researchers, members of the military, and academics from around the world at the NHCA Annual Conference, where there is something for everyone interested in preventing noise-induced hearing loss (NIHL).

This year's conference in St. Petersburg, Fla., was themed "The Art of Hearing Loss Prevention." The conference was well attended, and the presentations and workshops, as well as the discussions in the aisles, were wide ranging, engaging, and definitely quite passionate. Two major themes seemed to reverberate throughout the event: who's at risk and compliance vs. best practices.

Who's At Risk for NIHL?

Detecting hearing loss earlier: At the conference, NIOSH reported on a study of the prevalence of occupational hearing loss, comparing three definitions of Standard Threshold Shift (STS).

In 1998, NIOSH recommended non-age-corrected STS criteria of 15 dB at any single frequency. This proposed criterion is shown to identify noise-induced hearing loss significantly earlier in its progression. Even non-age-corrected OSHA STS criterion detects hearing loss earlier for better prevention. (The OSHA noise standard defines an STS as an average 10 dB or more loss in one or both ears relative to the most current baseline audiogram averaged at 2000, 3000, and 4000 Hz.)

The prevalence of age-adjusted OSHA STS definition was 6 percent, the prevalence of OSHA STS without age correction was 14 percent, and the prevalence of the NIOSH definition of STS was 20 percent.

Of interest, the NIOSH study is currently underway -- and would welcome additional participants with audiometric data -- to participate. For those participating, NIOSH will help to "de-identify" the data and include it in this vital "national data repository" of audiometric results. To request additional information or to participate in the NIOSH study, contact Dr. Liz Masterson at OHLSurveillance@cdc.gov.

Noise is more dangerous than previously thought. Researchers at Harvard Medical School revealed data that suggests neural damage continues for months after noise exposure has ceased. This neural damage could make tinnitus worse and make speech understanding more difficult, even if hearing remains the same.

Workers exposed to ototoxic chemicals are known to be at higher risk for hearing loss. The chemicals are common in some workplaces and even at home. They include solvents such as toluene and styrene. Toluene is used as a solvent in paints, inks, dyes, paint thinners, varnishes, and shellacs; it is used in nail polish, airplane glue, and other glues. Toluene is also used in printing operations and in the chemical, paint, and pharmaceutical industries and in petroleum refining. But what impact does exposure to ototoxic chemical have on hearing performance in daily life activities? A study by researchers at the University of Queensland in Australia showed poorer performance in not only detecting sounds (what we traditionally test with an audiogram), but also in temporal resolution and in self-reported hearing performance for workers exposed to ototoxic chemicals when compared to workers without ototoxic exposures. The researchers recommend that solvent-exposed workers should be included in hearing conservation programs and that these workers should be made aware of the adverse effects of solvents on the auditory system. Meanwhile, a researcher from West Virginia University proposed a battery of audiologic tests that could help to diagnose solvent-induced hearing loss.

Musicians are occupationally/recreationally exposed to hazardous noise. No doubt musicians don't think of the loud sounds they produce as "noise," but they can nonetheless be hazardous. A researcher from the University of Sydney in Australia reported that orchestral musicians face similar sound exposure in practice rooms as they do in performance and for longer periods of time. No matter the type of music, performers should be aware that practice contributes to their overall exposure. Recommendations to manage the sound exposure include: using mutes; practicing in an acoustically appropriate environment; using hearing protection -- some hearing protectors are designed to attenuate sound more naturally (these are called musician's ear plugs, flat-attenuation ear plugs, or uniform-attenuation ear plugs); and allowing ears a chance to recover by spacing practice sessions.

Another presentation reminded us that it's not just musicians who are exposed to hazardous noise in the entertainment industry, but also dancers, actors, stage crew, technical crew, etc. An initiative within the European Union to provide guidance for "event safety" includes hearing loss prevention. For many workers in the entertainment industry, especially musicians, hearing is a vital tool. Therefore, with proper engagement, cooperation between exposed workers and safety professionals can be very successful.

Compliance vs. Best Practice

How do I energize my hearing conservation training? The military has traditionally led hearing conservation efforts and continues to do so. A recent round robin study compared various ear plug fit-testing systems. It reported an average 6-14 dB improvement in protection after fit-testing and confirmed the benefits of ear plug fit-testing that are provided in the OSHA/NHCA Best Practice Bulletin: Individual Fit-Testing, which is available online at http://www.osha.gov/SLTC/noisehearingconservation/hearingprograms.html.

NIOSH reported on a study of ear plug fit-testing in a very high-noise environment and concluded that workers with low attenuation (not enough protection) benefited from ear plug fit-testing through training of how to fit the protector or selection of a different protector. Workers in this high-noise area were generally able to find an ear plug that provided at least 30 dB of protection, avoiding the need to de-rate well-fit ear plugs or require double hearing protection.

A partnership between NHCA and NIOSH bestows the Safe-in-Sound Excellence and Innovation in Hearing Loss Prevention Awards™ to honor excellent hearing loss prevention (HLP) practices. NIOSH Director Dr. John Howard presented this year's awards to Johns Manville, which was recognized in the manufacturing industry for its "Hearing Conservation Pyramid," an approach that looks at both leading and lagging indicators of hearing conservation program effectiveness. Vulcan Materials was the construction industry recipient for its data-driven hearing loss prevention program that goes beyond regulatory compliance. Dangerous Decibels® was recognized for its innovation, a multi-faceted, evidence-based intervention program dedicated to the prevention of noise-induced hearing loss and tinnitus.

Changing compliance regulations: 85-3, test 8kHz, extend age correction tables. There was a lot of buzz from leaders in hearing conservation about the 85-3 Coalition, where experts continued to advocate for evidence-based changes to compliance regulations. According to its website, 85-3 Coalition members are concerned professionals and organizations that aim to recognize real-world efforts toward making workplaces quieter, healthier, and more productive. The 85-3 Pioneers are progressive companies, agencies, and nations that have adopted the 85-3 criterion for the noise exposure assessment of employees. The body of evidence continues to grow that the use of the 5 dB exchange rate was based on faulty assumptions. The verdict that's becoming more and more apparent is this: Noise that includes impulses is more damaging and, as mentioned above, the neural damage from hazardous noise continues even after the noise stops.

However, this trend toward 85-3 is not without its critics. There is concern by some that any simple rule relating level, duration, and hazard is an over-simplification, and that a more accurate exchange rate may vary with noise conditions (impulse noise, rest periods, etc.). If your company uses 85 dB as your Action Level and 3 dB as your Exchange Rate for your hearing conservation program, consider becoming a Pioneer company.

Next Steps
How do you use this information in your hearing conservation program? One of the best characteristics of the NHCA conference is that you not only can learn about cutting-edge research, hear various perspectives on hearing conservation, and learn new ideas to take home to your hearing conservation program, but also you can network with experts, peers, academics, and service providers who are all willing to share their passion for preventing NIHL.

  • Should I add workers who are exposed to ototoxins to my hearing conservation program?
  • Should I continue to monitor hearing after workers are no longer exposed to hazardous noise?
  • Should I share my audiometric database with the NIOSH national repository?
  • Should I educate my workers about off-the-job noise risks, such as music-induced hearing loss or ototoxic exposure?
  • Should I evaluate the Action Level and Exchange Rate for my hearing conservation program?
  • Should workers exposed to both noise and ototoxins have a more protective Action Level and Exchange Rate?

If you need answers to questions such as these (or, at least, lots more information, perspectives, and advice), the annual conference of the National Hearing Conservation Association is a great place to, as its logo tagline says, "Join the Experts. Get the Expertise." The 2014 NHCA annual conference will be March 13-15, 2014 in Las Vegas.

This article originally appeared in the June 2013 issue of Occupational Health & Safety.

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