FAQ
Frequently Asked Questions
What is the NRR?
The NRR was planned to be a simple guide for consumers and professionals that would accurately indicate the amount of noise reduction, in decibels, that users might obtain when wearing a particular hearing protector. Higher numbers were intended to denote greater effectiveness, with values ranging from 0 to 33 dB. NRRs are computed from laboratory noise reduction measurements on human subjects wearing hearing protectors under optimum conditions.
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Why is it changing?
Many different studies over the last 25 years have shown that the NRR overestimates the amount of protection that most wearers obtain under normal wearing conditions. In response to these studies, OSHA, NIOSH, and even the hearing protector manufacturers themselves have recommended that the NRR be routinely reduced by a factor of 50% or more in order to better predict the effective protection provided by the device. This process, known as "de-rating," has caused confusion along with an OSHA requirement that employers subtract 7 dB from the NRR when it is used with noise exposure readings measured on the A-weighting scale. Finally, experts have expressed concern that a single number rating such as the NRR does a poor job of informing users that the actual performance of hearing protectors varies widely from one person to the next due to differences in the training, fitting ability, and motivation of the wearer. As a result,
the Environmental Protection Agency (EPA) has undertaken a process to revise hearing protector testing and NRR labeling.
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How will this help me in choosing hearing protection?
Certainly helping users select appropriate hearing protectors was the goal when the process of updating the NRR began. The EPA intended to make the NRR a better descriptor of the capabilities of hearing protectors as they are usually worn. Whether the proposed changes will actually achieve that goal is yet to be seen. If OSHA, NIOSH and others continue to call for de-rating of the NRR, it is likely that many consumers will not view the changes to the NRR labels as helpful.
Along with the concern over de-rating, the new NRR will not address the errors that occur when users attempt to predict the hearing protection achieved by an individual wearer from the average performance of a group of wearers. Though the new two-number system raises awareness of the potential for a range of performance values to be achieved by your workers, it does not tell you where in that range any one worker will fall. As a result, fit testing of hearing protectors to validate the noise reduction provided to each wearer will continue to be an important tool in occupational hearing conservation programs. There are a number of fit-test systems in the marketplace today. One of the most useful and quickest to apply is the E-A-Rfit™ Validation System. To learn more about
E-A-Rfit™ and fit testing in general, please visit www.e-a-r.com/pdf/hearingcons/0629.pdf.
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What is the main difference between the current and proposed new system?
The most obvious difference is that the single NRR number has now become a two-number range. The higher number of the new range is an estimate of the amount of protection that about one-in-five motivated and highly trained wearers would attain or exceed. The lower number is an estimate of the protection that four-out-of-five individually trained, but not necessarily motivated or highly trained wearers would meet or exceed.
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How will the new numbers compare to the existing NRR?
Early indications are that the current NRR will likely fall below the new upper value, closer to the new lower value, but it will vary by product. Until data are reported from hearing protector performance tests done using the most up-to-date test methods specified by the EPA (ANSI S12.6-2008, a document approved in September 2008), the exact numbers are still open to question.
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Does the new NRR affect the octave-band data that manufacturers have also provided?
The octave-band data will still be available and is essentially unchanged. However, those data will be computed from the new Method-A test results and, thus, may be affected by the new procedures.
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What do changes in NRR mean to me?
Since the new NRR labels will show a range of performance for the hearing protector, you may be more aware than in the past that the protection provided by a hearing protector depends as much on how well the wearer fits the device as on the noise-blocking properties of the device itself. As with all safety equipment, fitting and using the device correctly is critical to the level of protection achieved.
Perhaps more important will be the policies established by OSHA regarding how employers must use the new NRRs to comply with their Occupational Noise regulation, 29 CFR 1910.95. Since appendix B of that regulation now specifies the proper methods for using the existing NRR, it's quite possible that OSHA will issue new policies concerning compliance with those requirements. For example, OSHA has not commented on which NRR value, the higher or lower value, should be considered when evaluating whether a hearing protector provides adequate noise reduction. Likewise, it is not known at this time if OSHA will require employers to apply a de-rating to the new NRR.
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How soon will the newly revised NRR labels appear on packages of hearing protectors?
The date for all manufacturers to incorporate the new NRR on packages of hearing protectors has not been announced. If a proposed rule appears soon, as anticipated, and a final rule appears in 2009, it would probably be at least another 12 to 18 months before manufacturers would be required to meet the new rules. This time would be needed to allow for retesting all of the hearing protectors using the new test method, updating packaging, and getting the new products into the distribution system.
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Will it be necessary to incorporate a correction factor of 7 dB to the new ratings?
No. Unlike the old NRR that was intended for use with dBC measurements, the new NRR is designed to be subtracted from the A-weighted
noise measurements so that no 7-dB adjustment will be required.
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Does following the new labeling guarantee that my employees will be adequately protected?
Regardless of what changes are made to the NRR, it is still a description of the average noise reduction obtained by a group of wearers and cannot be used to accurately predict the amount of noise reduction obtained by an individual. The only way to gain confidence in the protection level for individual wearers is to conduct fit validation—a test of each person wearing his or her own hearing protector that documents the level s/he receives from that protector. Use of these fit validation systems in industrial hearing conservation programs is steadily increasing. To learn more about them, please visit www.e-a-r.com/pdf/hearingcons/0629.pdf
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What is the EPA's role in the new standards?
The EPA was empowered by Congress in the late 1970s with the legal responsibility to regulate the hearing protector testing and labeling. The current HPD rating and labeling rule (40 CFR 211 Subpart B) has been in place since 1979. Despite good intentions, the EPA Noise Reduction Rating does not inform users how well hearing protectors work for them in real-world situations. In fact, the rating itself and the information that accompanies the NRR may mislead users into thinking that they are obtaining more noise reduction than is actually the case. This has led to an OSHA policy of de-rating, described above, when employers use hearing protectors as a substitute for noise controls in hearing conservation programs.
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Will I have to replace my current hearing protection?
It is unlikely that hearing protectors will have to be replaced. However, in some critical noise situations, employers may wish to choose different devices based on re-evaluation of the hearing protectors being used, the new NRR, and the variability in the average protection obtained by groups of workers and the individual protection obtained by specific employees. As employers become more familiar with the new NRR values and the variability in performance among individuals, it is expected that many will choose to implement fit-testing systems to better assign devices, and more importantly to better train and motivate their workers.
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How will this impact de-rating?
As stated above, the EPA's intention was to specify a rating system that would not require de-rating. At this time it is unknown whether that goal has been met since only a few devices have been tested to the new Method-A procedure in ANSI S12.6-2008 and no labeled data are available. Based on preliminary laboratory testing conducted in the fall of 2008, it appears that de-rating may still be necessary to adjust the NRR to more closely match the real-world noise reduction most users can obtain. If the practice of de-rating persists in the era of the new NRR, it seems likely that individual fit testing will be recognized by more and more employers as the most accurate method for estimating the ability of hearing protectors to reduce the noise exposure of individuals who wear those devices.
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