Page 34 - 2016Spring

Preventing Occupational Hearing Loss
Figure 4. Product noise rating (PNR) noise emission rating product label (left panel) and an informative noise emission declaration label (right panel). Adapted from Nobile (2011).
2,000 to 6,000 Hz range can present an increased risk compared to that at lower frequencies. Note that the ISO 9296 declaration in Figure 4 is strictly an informative declaration; there is no comparison to other similar products. Also note that unlike the PNR declara- tion, there is no overall noise scale, so the consumer might have no idea of whether 6.9 bels is “quiet” or “loud.”
Advocacy
While most individuals are aware that exposure to excessive noise over time can result in hearing loss, they may not be aware of the implications of hearing loss for health and quality of life, rec- ommended exposure limits, or effective methods of prevention. Fundamen- tal information can be found on the NIOSH Buy Quiet topic page: http:// www.cdc.gov/niosh/topics/buyquiet/.
the product when it is operating and when it is idling. The numbers on the right half are the “emission” sound pressure level when the product is operating and when it is idling. These measurements are made in a controlled environment such as a hemi-anechoic room. For assessing the risk of noise-induced hearing loss, an industrial hygienist will need to know the sound pressure level at the ear in the actual en- vironment where a worker might be positioned, and this is very different from the emission sound pressure level on the declaration.
As mentioned previously, the sound power level is the best descriptor of the noise emitted by a product and is the quan- tity most useful for predicting workplace noise levels. Ad- ditional information could be included with the informative declaration. That is, the sound power spectrum could be included in secondary information. The spectrum is criti- cal to determining risks because sound with content in the
1 The unit “bel” has been introduced by the Information Technology industry as the unit of sound power level in ISO 9296 (1988) and in ANSI S12.10 Part 2 to distinguish it from sound pressure level for which the unit is the decibel. Except for the IT industry, the bel has not been widely accepted for other product types and the decibel (with A-frequency weighting) is commonly used as the unit of both sound power level and sound pressure level. Thus, the quantity being specified (sound pressure or sound power) must be indicated in the text.
Primarily, companies want to understand the return on the dollars invested in health and safety programs such as Buy Quiet.
Informational graphics are available for download and print- ing to motivate workers to identify processes that will reduce the noise levels in a work place. Every noise control engineer is taught to look for the simple controls first. If panels are loose, then tighten them. If a part is rattling or vibrating and can benefit from extensional damping, then fix it. If pulleys and belts are squeaking, they need attention. Targeted mes- sages have been developed for employees in manufacturing and construction. Educational videos and audio demonstra- tions are available to promote the concepts of why noise con- trol is important.
Starting in 2009, NIOSH and the National Hearing Conser- vation Association partnered to develop the Safe-in-Sound Award for Excellence in Hearing Loss Prevention and Inno- vationTM (www.safeinsound.us). The Safe-in-Sound Commit- tee accepts applications from companies, rigorously reviews them and conducts site visits. The awards for corporations have focused on industries in the manufacturing, construc- tion, and services sectors. The results of the Safe-in-Sound Awards indicate that advocacy can have a significant effect.
United Technologies
In 2015, United Technologies Corporation (UTC) was rec-
32 | Acoustics Today | Spring 2016