Everyday Noise
Suggestions for Protecting Our Hearing in a Noisy Society
I was researching a chemical online when I heard it: the roar of lawnmowers and leaf blowers. It was the landscapers at work on my neighbors’ yard.
I closed the window, but I still couldn’t concentrate. Finally I went out to speak to one of the guys operating a leaf blower. “You’re not wearing hearing protection,” I told him. He said he didn’t need to. “Over time,” I told him, “you’ll lose your hearing.” He replied, “Not a problem.” I turned and walked away, thinking I should approach the owner of the company about hearing protection training.
DAILY NOISE We live in a noisy society. Escaping noise seems almost impossible in our day-to-day lives. I’ve taken noise dosimetry readings while riding my bicycle to and from work. During these short, one-hour rides, I receive 10–14 percent of my ACGIH dose of noise. Sometimes I wear hearing protection while cycling. I can still easily hear cars and horns; the traffic noise is a lower frequency and goes through the ear plugs. I don’t feel that wearing ear plugs negatively impacts my environmental awareness and general safety. After all, cars have built-in noise isolation, and drivers can still hear horns. During a meeting of AIHA’s Noise Committee, one member mentioned that workers in her company’s control group—people who aren’t occupationally exposed to noise—​were losing their hearing. This is a direct result of our noisy society and the environmental noise we are exposed to every day.

"I've taken noise dosimetry readings while riding my bicycle to and from work. During these short, one-hour rides, I receive 10-14 percent of my ACGIH dose of noise."
OUTREACH TO CHILDREN Modern society has sources of noise that were unknown just a few years ago. When I cycle on trails, I’ve tried to inform walkers of my presence, but the earbuds they’re wearing drown out the small bell I use to ring my presence. I have to shout to let them know I’m passing them. In response to the prevalence of noise, researchers at Oregon Health and Sciences University, in collaboration with colleagues at the Oregon Museum of Science and Industry, developed an intervention program called Dangerous Decibels. This program is directed toward school-age children and is designed to change their knowledge, attitudes, and behaviors related to hearing health. It focuses on answering three key questions:
• What are the sources of dangerous sounds?
• What are the consequences of exposure to dangerous sounds?
• How do I protect myself from dangerous sounds? 

Individuals are trained to use three strategies to protect themselves from dangerous sound levels: 
1. Turn it down. 2. Walk away. 3. Protect your ears. As described in the January 2009 issue of Seminars in Hearing, Dangerous Decibels is using new theories of learning, such as the Theory of Reasoned Action (TRA) and the Theory of Planned Behavior (TPB), to try to change the behavior of children and workers. These theories attempt to describe the link between attitude and behavior. Dangerous Decibels holds two-day educational workshops to train educators to deliver the Dangerous Decibels program in their communities, schools, and workplaces. Public workshops are posted to the Dangerous Decibels website. (You can also contact Dangerous Decibels to request future notifications or indicate your interest in hosting a private workshop for your organization.) The Dangerous Decibels program is now being used in a number of countries, including New Zealand, Israel, China, Brazil, and Singapore. According to Deanna Meinke, co-director for Dangerous Decibels, efforts continue on many fronts, including a community-based participatory research project with Native American tribes. Recently, in recognition of the need to widely disseminate the program, 3M has sponsored a number of Dangerous Decibels workshops and a conference. One of the program’s successes is a clever exhibit that educates the public about the risk of listening to loud music. The exhibit is a mannequin equipped with a simple sound level meter whose microphone is embedded in the mannequin’s ear canal to show the actual sound levels of music in earbuds. Nicknamed “Jolene,” the mannequin can be used to demonstrate whether a given volume on a music player is hazardous based on the duration of listening. (If you’re interested in building a Jolene for your own educational outreach, you’ll find complete instructions on the Dangerous Decibels website at http://bit.ly/joleneinstructions.)

"Walking away from noise in our community is not as difficult as it may seem. Industrial hygienists are familiar with the general rule of thumb: when we double the distance from a source of noise, we subtract 6dB; when we halve the distance, we ad 6dB."
WALK AWAY Walking away from noise in our community is not as difficult as it may seem. Industrial hygienists are familiar with the general rule of thumb: when we double the distance from a source of noise, we subtract 6 dB; when we halve the distance, we add 6 dB. When distances are not divisible by or a multiple of 2, we use the formula from Quantitative Industrial Hygiene: SPL2 = SPL1 + 20 Log [d1/d2], where: 
SPL2 = sound pressure level at d2 
SPL1 = sound pressure level at d1 dn = distance from source
When I was commuting to work on my bicycle, I would use this concept to move to the right at intersections. I have measured the road noise from traffic at 92 dBA, and my distance in the bike lane is five feet from traffic. If I move out to fifteen feet, the noise level using this formula is only 82–83 dBA.
CONTROLS IHs talk about personal protective equipment (PPE) all the time, and that includes hearing protection. Recent advances such as fit-testing of ear plugs have made the PPE option better, but if we look at the principles of exposure risk assessment and management (ERAM) and the hierarchy of controls, we see that elimination and substitution are the best alternatives. How can we eliminate noisy equipment? I did it with my lawnmower: I now use the older-style push-pull rotary mower, which produces no noise and provides a much more pleasant experience mowing the lawn. (Also, I get some needed exercise.) We need to turn down the noise in our environments, both on and off the job. As industrial hygienists, we use the principles of ERAM to assess and manage risks. We anticipate and recognize the hazards of noise, make an evaluation, and look at controls. One simple engineering control is to buy quieter tools and machines. NIOSH promotes this concept through its Buy Quiet program. The Buy Quiet website compares the sound levels of various tools and identifies quieter options. For example, the website compares a circular saw that produces a 107 dBA output with an almost identical saw that produces only 96 dBA—a 90 percent reduction in noise energy. Even though hearing protection is still necessary with the quieter saw, its lower noise output means that the protection will be more effective. The difference between the eight-hour ACGIH TLV of 85 dBA and the less noisy saw is 12 dBA, whereas this difference with the noisier saw is 22 dBA. 
(Remember, the Noise Reduction Rating for hearing protection needs to be modified by the derating formulas to achieve real-life exposure estimations. See the sidebar for more information.)

NIOSH lists these benefits to Buy Quiet: • reduces the risk of hearing loss • reduces the long-term costs of audiometric testing, personal protective equipment, and workers’ com​pensation (NIOSH estimates that purchasing a quieter product provides $100 of savings per dBA) • helps companies comply with OSHA and other noise regulation requirements • reduces the impact of noise on the community
NIOSH recommends that companies inventory their equipment for noise and replace the noisiest equipment with quieter models. When new purchases are needed, NIOSH encourages companies to put specifications for noise emissions in the equipment requirements and to replace equipment with quieter alternatives. You can find out more about the noise levels of various power tools from the NIOSH PowerTools Database at http://bit.ly/ nioshpowertools.

"NIOSH recommends that companies inventory their equipment for noise and replace the noisiest equipment with quieter models."
PLUGS AND MUFFS FOR EXTREME NOISE EXPOSURES Hunting season is almost upon us, and that means more people will be using recreational firearms and shooting in target ranges. Noise damage to the ear from firearms is instantaneous, and can be severe. Rifles and pistols can have noise levels of 140 dBA and higher. The NIOSH alert Preventing Occupational Exposures to Lead and Noise at Indoor Firing Ranges recommends that participants wear double hearing protection (plugs and muffs) for indoor firing ranges. (The publication is available at http://bit.ly/nioshfiringrange. It also includes recommendations for preventing exposures to lead for those doing maintenance in firing ranges.) These recommendations hold for other extreme noise exposures, such as jet engine testing, flight lines for military or commercial jets, and military gunnery. The sense of hearing is important in hunting, both for birds and big game, so protecting your hearing while hunt​ing is more difficult. But hunters have some options. Ear plugs can work well, but they restrict the sounds hunters need to identify their game. For hunting from a stand, earmuffs are a good choice since hunters can put them in place prior to taking a shot. For hunters who walk through the woods, earmuffs are more difficult to use. Last year the magazine Guns and Ammo published an article, “G&A Basics: The Science of Hearing Protection,” that discusses an alternative to earmuffs. These “electronically-enhanced hearing protection devices,” which are muffs with microphones and speakers, amplify outside sounds and shut down sound transmission when dangerously loud sounds are detected. (The article is available at http://bit.ly/ gunshearingprotection.) The important idea is to act to protect our hearing, and that of our families and workers, rather than simply allowing our noisy society to trample our inner ears. If we don’t, then by the time we reach retirement age we may not be able to hear the sounds we want to enjoy—birds chirping in the morning, a wonderful soprano singing an old favorite, or simple silence—without the ringing in the ears caused by tinnitus. Oh, and the landscaper who was using the leaf blower was wearing hearing protection the next week.
The 411 on the NRR​ EPA’s Noise Reduction Rating (NRR), promulgated in 1979, was intended to characterize the effectiveness of hearing protection devices (HPDs). The idea behind the NRR is simple: the higher the rating, the more effective the HPD.
But this simple concept is complicated by the logarithmic nature of noise exposure. If we use an HPD with an NRR of 30 dBA, for example, we aren’t actually lessening exposure by 30 dBA. Actual exposures with a given HPD need to be calculated using a “derating” formula.
The derating formula recommended by OSHA is

Estimated Exposure (dBA) = TWA (dBA) - [(NRRh - 7) x 50%]
For someone using a 96 dBA circular saw and ear plugs with an NRR of 22, this formula yields an estimated exposure of​
96 dBA - {[22-7] x 50%} = 85.5 dBA
In contrast, the estimated exposure with a 107 dBA saw is 99.5 dBA. More information about the OSHA formula is available from http://bit.ly/oshaattenuation.
If we use the ACGIH TLV as our exposure limit, the quieter saw will al​low a little more than 7 hours of use, while the noisier saw would result in an overexposure in about 17 minutes, with the user wearing the hearing protection. Without hearing protection, the noisy saw allows only about 3 minutes before overexposure, whereas the less noisy saw allows ​about 38 minutes. The formula for determining these estimates is

TN =                     
​​2(L — 85)/3
where “T” is the exposure duration and “L” is the dBA level. This formula is derived from AIHA’s Noise Manual. The original formula uses the OSHA PEL of 90 dBA with a 5 dBA exchange rate. I have modified it here for use with the TLV of 85 dBA and a 3 dBA exchange rate. More information on the use of the 85-3 concept is available from the website of the National Hearing Conservation Association at http://bit.ly/85-3coalition. —John Ratliff​


is a member of the AIHA Noise Committee. He can be reached at john.conklin​.ratliff@gmail.com or (503) 645-5467.​