Left blind and deaf at 18 months old from a serious illness, Helen Keller overcame her disabilities to become a renowned author and educator. According to Helen Keller, losing her hearing was a greater loss than losing her sight. "The problems of deafness are deeper and more complex, if not more important, than those of blindness. Deafness is a much worse misfortune. For it means the loss of the most vital stimulus the sound of the voice that brings language, sets thoughts astir and keeps us in the intellectual company of man."
It's ironic that we lose our hearing through the act of hearing. Years of chronic exposure to loud sounds slowly and painlessly steal our hearing. This noise-induced hearing loss generally goes unnoticed until it interferes with communication. By then it's too late. The damage cannot be repaired.
Hearing conservation programs play a critical role in preventing noise-induced hearing loss. But are our hearing conservation programs all they can be? A good hearing conservation program uses engineering and administrative controls to reduce employee noise as much as feasible before resorting to personal protective equipment. But most health and safety professionals managing hearing conservation programs are not acoustical engineers or experts in noise control. We're generalists, juggling hearing conservation along with other programs. The result can be an over-reliance on hearing protection.
What we need is an easily accessible source of noise engineering control solutions. Thanks to the Washington State Department of Labor and Industries, we have one in the Noise Reduction Ideas Bank (www.lni.wa.gov/Safety/Topics/ReduceHazards/NoiseBank). The Noise Reduction Ideas Bank is a searchable collection of noise reduction ideas that help identify ways to reduce workplace noise. The bank currently has a total of 100 records covering general industry and construction noise control techniques.
The bank's two drop-down menus make it easy to search for records by noise source, industry or both. The site also provides a keyword search function. In addition to the industry-specific noise reduction ideas, a search by specific industry also provides a list of 66 additional general noise reduction ideas. A search by noise source returns a list of all records for the particular source.
Combining an industry search with a noise source search supplies a list of noise control ideas for the source in the specific industry, plus a supplementary list of all other records for the selected noise source. For example, a search on "saws" in "carpentry" returns three hits specifically for saws used in carpentry, and 13 additional records.
While the bank database, with just 100 records, is small, it contains some wonderful ideas that can significantly reduce noise exposures at minimal cost. One of the hits on the saws in carpentry search is a link to the Government of Western Australia Work Safe Buy Quiet Selecting a Saw Blade Web page (www.safetyline.wa.gov.au/pagebin/pg000167.htm). The page provides three simple, yet effective, rules for selecting saw blades to reduce circular saw noise:
- Choose a saw blade with the greatest number of teeth, with the smallest width, suitable for the job to reduce noise by up to 6 dB.
- Choose a saw blade with built-in vibration damping to reduce noise by as much as 10 dB.
- Choose a saw blade with gullets as small as possible to reduce noise by 7 dB.
The authors point out that a 10-decibel reduction means a 90-percent reduction in the amount of sound energy, which means the sound sounds half as loud to the ear. Such an amazingly simple, low-cost noise control should be universally adopted.
I discovered the Noise Reduction Ideas Bank mousing around the Council for Accreditation in Occupational Hearing Conservation (CAOHC) Web site (www.caohc.org/index.html). The CAOHC trains and certifies occupational hearing conservationists and their Web site has some neat links on noise and hearing conservation.
The CAOHC site's Supplementary Teaching Tools page contains information on three free compact discs available from the Acoustical Testing Laboratory at the National Aeronautics and Space Administration (NASA) John H. Glenn Research Center (www.caohc.org/nasa.html). Two of the discs, Auditory Demonstrations in Acoustics and Hearing Conservation and Auditory Demonstrations II: Challenges to Speech Communication and Music Listening, illustrate fundamental acoustic principles, simulated hearing loss and how noise and hearing loss interfere with communication. The third disc, JeopEARdy, is an interactive multimedia game for employee education in occupational hearing conservation programs.
Order your discs by visiting the Acoustical Testing Laboratory Web site at www.grc.nasa.gov/WWW/AcousticalTest/HearingConservation/Main.htm. While visiting the site, be sure to check out NASA's Buy Quiet and Quiet by Design programs. You just might get some ideas for your own noise control program. The NASA site also has two children's activity work sheets on acoustics and noise.
Construction
If your hearing conservation program covers construction and maintenance activities, then surf on over to the Laborers' Health and Safety Fund of North America (www.lhsfna.org). Select the "Noise" item on the site's "Occupational Safety & Health" heading and benchmark your program against the Controlling Noise on Construction Sites best practices guide.
The easy-to-read guide has excellent information on hearing conservation techniques that work in the challenging world of construction hygiene, including a discussion of noise perimeter zones (NPZ). NPZ are designated high-noise areas roped off and marked to keep out workers who don't have to be there. Designated high-noise areas are common in general industry. There's no excuse for not applying the concept to construction.
Other Resources
The Internet has many other sites with helpful information. OSHA's Noise and Hearing Conservation page, of course, is the font of all regulatory knowledge. Now, it contains a link to the results of the agency's alliance agreement with the National Hearing Conservation Association (hearingconservation.org/ns_allianceNHCA_OSHA.html), including a new OSHA eTool for Noise and Hearing Conservation.
NIOSH's Noise and Hearing Loss Prevention (www.cdc.gov/niosh/topics/noise) Web page contains a useful Hearing Conservation Checklist and Hearing Protection Device Compendium. The site also has a great interactive sound level meter that displays sound levels of common work place sounds.
The Electronic Library for Construction Safety and Health (eLCOSH, www.elcosh.org) has an interesting collection of articles, ideas and training materials for the hard hats among us.
We don't know if modern medicine could have prevented Helen Keller's tragic loss. But we do know that a good hearing conservation program, especially one that uses engineering controls to reduce noise exposure, can prevent noise-induced hearing loss. Take advantage of Web-based noise control resources. Share your ideas with the rest of the world by submitting them to the Noise Control Ideas Bank. Working together, we can make a difference.
Contributing Editor Michael Blotzer, MS, CIH, CSP is an occupational hygiene and safety professional, writer and computer enthusiast who brakes for animals on the information superhighway. He can be reached by mail addressed to Occupational Hazards or by electronic mail at [email protected].