Noise-induced hearing loss is the world’s most prevalent and permanent occupational disease. While many hearing conservation managers endeavor to provide their workers with sufficient hearing protection and training, there remains the ongoing challenge of balancing hearing protection, situational awareness and two-way communications.
And while this balancing act affects nearly every worker who is at risk for noise-induced hearing loss (NIHL) in any situation, another segment of workers also must manage communications in extreme noise environments. These workers face a different set of challenges – specifically, the need to intelligibly understand and communicate using radios while protecting themselves from hazardous noise exposures.
In this article, we will review the options hearing managers can employ to strike an appropriate balance among the challenges of achieving hearing protection, situational awareness and two-way communication.
Dual Protection Challenges
In high-noise environments, hearing conservation program managers must balance adequate hearing protection without over- or under-protecting their workers. Too much protection, and a worker may not hear the nearby forklift backing up towards them. Too little protection, and the worker still may be at risk for noise-induced hearing loss.
In high-noise environments above 100-105 dB, workers often are required to use dual protection – earplugs and earmuffs. Dual protection often is the only available method to achieve maximum protection from hazardous noise. Using earplugs and earmuffs concurrently isolates the wearer, so it is warranted only in extreme noise levels. When calculating the maximum attenuation of dual protection, add five decibels to the highest published noise reduction rating (NRR) of either hearing protector. With the highest NRR of 33 decibels (dB) available in single-use foam earplugs, the cap of published protection will be 38 dB, which in some circumstances is not enough protections for extreme noise exposures.
Additionally, in hot and humid environments, workers often do not like to wear both earplugs and earmuffs. The added bulk and head coverage of earmuffs can cause discomfort among workers who are required to wear dual protection during their entire workday.
The following solutions, featuring the latest in hearing conservation technology, provide hearing conservation managers with real-world options:
Tech Solution #1: Earplug fit testing to determine actual protection. While the NRR provided for each hearing protector is only a laboratory estimate, new earplug fit testing systems can provide a personal attenuation rating (PAR) for any given earplug in each ear. This PAR approach verifies and documents how much attenuation a worker gets with an earplug and its appropriateness in a variety of noise environments.
In fact, in some instances, a worker may achieve more than the published NRR and may be able to “test” out of the use of dual protection. One flooring manufacturer in Georgia recently implemented earplug fit testing to do exactly that.1 At Shaw Industries, workers who could prove the fit of their earplugs protected them to below 82 dB could “graduate” out of dual protection. “And as temperatures rise in the summer, workers have been eager to ‘get certified’ on their earplugs in order stop using dual protection. Not only do their employees love not having to wear ear muffs in hot, humid weather, it saves the company some expense as well.”1
Tech Solution #2: Personal sound exposure monitoring (PSEM) to determine the actual protected noise exposure as a dose that a worker accumulates during the course of a workday. PSEM devices integrate a personal dosimeter into a hearing protection device and measure and record a worker’s actual noise dose over their entire work shift. When a PSEM device is worn as hearing protection, it measures sound pressure levels interior to the protector. During periods when it is not worn, in-ear dosimeters measure the ambient noise level, which is equal to the exposure impinging on the ear. Overall, it accounts for the ear’s actual noise exposure and provides realtime monitoring throughout the workday.
One company used a PSEM technology to measure worker exposures in extremely noisy areas where double protection was not enough.2 PSEM measurements helped determine that workers were protected to safe levels and did not require the use of dual protection.
Changing Noise Environments
Most passive hearing protectors and communication headsets are designed for use in constant noise levels and only offer passive protection. Most passive HPDs do not adapt to changing noise levels (eg. intermittent or impact noise). Many workers who wear communication headsets are mobile and are exposed to a wide range of noise during their workday. For these workers, carrying and changing into different hearing protectors is not an option.
Tech Solution: Intelligent hearing protectors that feature adaptive “hearthrough” technologies. Such intelligent HPDs not only provide an appropriate amount of passive hearing protection, but external microphones actively listen to all ambient noise and automatically reduce impact or intermittent noises to safe levels in the ear. This type of digital sound processing technology, pioneered with hearing aids, is designed to seamlessly maximize the listening capability of the worker. The device’s digital impulse protection automatically minimizes impact or intermittent noises without compromising listening quality.
Speech Intelligibility
In high-noise environments, workers often must strike a balance between protecting their hearing and communicating with coworkers, either face-to-face or through two-way communication radios. In both instances, it takes a great deal of concentration to pay attention to incoming communication. While wearing passive hearing protectors, a worker may not fully hear the conversation and must look for visual clues to understand its content. When wearing communication headsets, a worker may raise the volume of the headset to compensate for the high ambient noise. Others may remove one ear cup to receive the incoming communication, which puts them at risk for hazardous noise exposure.
The speech intelligibility of outgoing communications also is a concern. Many two-way communication headsets feature a boom microphone, which picks up not only the worker’s voice, but also environmental sounds that may compromise clear communication. In a critical situation, where the urgent, outgoing command is “Get back!” and the incoming command instead is heard as “More slack,” this could put the worker and others at additional risk.
Tech Solution: In-ear intelligent hearing protectors that incorporate voice pick-up from inside the ear canal. Such systems use air or bone conduction to pick up the voice without compromising the sound with ambient noise exposures. This also enables workers who are required to wear other personal protective equipment, such as respirators that can block or muffle external microphones, to communicate more clearly and effectively, especially in hazardous situations.
Staying in Touch
As important as it is to be protected from permanent noise damage and to communicate despite high noise, it’s equally necessary for workers to remain in touch with their surroundings. Imagine the danger created by not hearing an alarm or the sound of nearby machinery that could put workers and teams at risk of accident.
Tech Solution #1: Sound amplification earmuffs that amplify ambient sound to safe levels while acting as a passive hearing protector. Such earmuffs not only enhance workers’ awareness of their environments, they also can hear important communications without removing an ear cup.
Tech Solution #2: Hearing protectors with active noise reduction (ANR) and other intelligent hearing technologies seamlessly reproduce sound, naturally and clearly, without affecting high noise attenuation. And they do so automatically, using ultra-fast, hands-free digital processing. This technology also overcomes the potential hazard created when workers use one ear cup and leave the other off in order to maintain contact with their surroundings, thus exposing that ear to hazardous noise.
The Sound of Productivity
In addition to the personal safety and hearing loss prevention aspect of incorporating these new technologies into occupational hearing conservation programs, there is an added benefit: worker productivity.
Highly skilled workers who are adequately protected (and monitored) in extreme noise environments above 105 dB may be able to work longer in such areas. Be they in such high-noise environments as sandblasting on a construction site, pouring steel in a forge plant or in the vicinity of helicopter landings on offshore oil platforms, ultimately, the benefits of investment in protecting your workers with these new hearing conservation technologies can have positive outcome on a company’s bottom line.
Renee S. Bessette, COHC, is the global brand manager for Honeywell Safety Products and is responsible for marketing communications and global brand management for the Howard Leight brand. She has a B.A. in journalism from the University of Rhode Island and has served as the commercial member delegate on the National Hearing Conservation Association executive council. Contact Bessette at [email protected]
1Case study. “VeriPRO ear plug fit testing.”.. http://www.hearforever.org/shaw 2Case study. “QuietDose In-Ear Dosimetry...”
http://www.hearforever.org/dixie