What’s wrong with NRR? Choose A or B

March 30, 2011

Since 1974, hearing protection potential has been measured by testing hearing protection under a methodology described in the ANSI standard S3.19-1974.  In that standard, researchers set out to measure the optimal protection potential of a hearing protector. This test methodology has become the “Gold Standard” for hearing protection attenuation measurement. Since that time, researchers have discovered that the “potential” afford by a hearing protector is seldom achieved in actual use. “>The seminal research on this subject was a compendium of studies compiled in 1994 by Elliot Berger (AEARO), John Franks (NIOSH), and Fredrick Lindgren (University of Gothenburg).  In that research they determined from previous research that the average attenuation from a foam plug was 46% of it’s labeled NRR.  Likewise, a molded 3-flange plug afforded 17% of what its potential might be; muffs 65%.

These results are averages, however, and therefore not applicable to specific individuals.  How does a hearing conservationist apply this information to specific individuals? The answer is, you can’t.Jordan Retro 4.

Once the discrepancy between the NRR and what noise reduction wearers were actually achieving was well documented, conservationists struggled for a way to approximate hearing protector attenuation with little except the NRR to rely upon. OSHA and NIOSH, developed similar formulas to de-rate the NRR of a hearing protector in an attempt to provide hearing conservationists with a more realistic estimation of real world protection values. The OSHA formula for applying the NRR to determine the users exposure level (PEL), starts with the NRR, and first adjusts it for the different scales used to measure sound (The A scale for as the ear hears at moderate levels and the C scale for how loud noise is measured on a more linear frequency response).  If the dBA scale is used, the NRR is reduced by 7 before subtracting it from the TWA (Time Weighted Average) exposure level in dBA.  If the TWA was measured on the dBC scale, then the NRR is simply subtracted from the dBC TWA.  A field directive of OSHA  (OSHA Instruction CPL 2-2.20B, February 5. Field Technical Manual (pp. 4-1 – 4-15), Rockville MD: Government Institutes, Inc.) instructs that the NRR (or adjusted NRR-7) should be halved before subtraction from the TWA exposure.  “>NIOSH and OSHA differ on the order of these computations. NIOSH recommends dividing the NRR by 2 and then subtracting 7 if using a TWA measured in dBA.  OSHA prefers to subtract 7 and then divide by 2.Jordan Shoes For Women

In practice, let us presume you have a hearing protector with an NRR of 33 and a TWA exposure measured in dBA.  For NIOSH’s purposes you would rate that protector as… 33/2 = 16.5-7 = 9.5dB.  OSHA would rate this protector as 33 – 7 = 26/2 = 13. As you can see, whether you use 9.5 or 13 for the Real World Reduction of this protector, you are a long way from the original, labeled NRR of 33 dB.  Hearing conservationists don’t like the de-rating approach because it speaks to averages, is not really reflective of true design differences between various protectors, and does not specify what the person they are trying to protect will achieve. Their goal is zero hearing loss. Even the most conservative estimation can still be wrong up to 5% of the time.  Regulators don’t like de-rating for the same reason – the lack of specificity.  Manufacturers don’t like it as it isn’t, by nature, accurate. It only approximates an average result. Since no one likes the de-rating approach developing a test methodology to yield more accurate estimates of real world attenuation was desired.

This realization spawned a search for an alternative standard; one that would predict the noise reduction a wearer might reasonably expect to get. The resultant standard, ANSI 12.6-1997 (R2008) contained a similar method to that of the original standard for hearing protector attenuation “potential” with some slight modifications. Also, and for the first time, ANSI 12.6 included a second standard for measuring the hearing protection a naive wearer, using the protector for the first time, with only the manufacturers printed instructions to rely upon might achieve.  These two methods for determining hearing protector attenuation (protectiveness) were labeled Method “A” and Method “B” and their resultant ratings NRRa and NRRsf (where the sf stands for Subject Fit).

Research into the applicability of the new NRRsf standard unequivocally demonstrated that it produce attenuation values that were very close to what people received when they first starting wearing a hearing protector.  As a result, NIOSH (National Institute of Occupational Safety and Health) and OSHA both supported accepting this as a measure of the “Real World” attenuation.  Now finally the hearing conservationist had a measure they could rely on for determining whether a given hearing protector would work in their facility. What could be better? As it turns out, lots. (to be continued in a future blog).Women Jordan Shoes.

 

It was a tough year for workers.

January 24, 2011

2010 was tough year for workers in noise in both the U.S. and Canada. First the EPA tried to address problems with the labeling of hearing protectors. What problems? Well, currently the label on a hearing protector tells workers of the potential hearing protection that could be obtained from a protector. The problem is that few achieve this level outside of the laboratory. The problem is so acute that OSHA (Occupational Safety and Health Administration) insists companies de-rate hearing protection (by a lot) when calculating how much protection they need to give a worker. This de-rating lowers the protection value of a hearing protector with a lab rating of 30 to 11.5. – over 60%.

So the EPA asked the ANSI working group on hearing protection for a better way to rate hearing protection while still measuring the “potential” of the protector.  The new rule will provide 2 numbers for rating hearing protection. The lower of these 2 numbers will be higher than the number used today (meaning further away from what happens in the real world – back to the drawing board).

OSHA announced yesterday that it is withdrawing its proposed noise interpretation that originally appeared in the Federal Register on October 19, 2010. OSHA had planned to insist companies with noise levels above 90 dB, engineer out the noise because hearing conservation programs are not working. They point to the fact that since 2004, 125,000 workers have had permanent damage to their hearing.  OSHA, after meeting with Senators Leiberman and Snowe, of the Senate Committee on Small Business and Entrepreneurship Sens. Snowe and Lieberman are also co-chairs of the Senate Task Force on Manufacturing.  Canadian regulations tend to follow the U.S. as these economies are closely linked.

So hearing protection labels are more misleading and no one will have to reduce the noise their factories make.  It was a tough year for workers in noise. Better toughen up your ears.

The Sound of Hearing

December 11, 2010

Recently I was having a conversation with Mary Gallert, a doctor of audiology at Hearing Healthcare Associates, LLC.

in New York state  about protecting children’s hearing.  Many children are in some form of music instruction in school and Dr. Gallert’s review of available literature revealed that there appears to be no widely accepted protocols for protecting their hearing.  When schools ask her for guidance, she does not have any protocols to fall back on.  Hmm, seems like a problem brewing and especially for their instructors.Black Friday Ugg Boots .

I went to an expert in the field for an answer. Marshall Chasin is the director of Auditory Research at Musicians’ Clinics of Canada. Marshall’s feedback is

I would suggest that the students get a pair of ER-20 (also known as Hi-FI  ($12.95) from www.etymotic.com ). In many cases, serious music students get the ER-15 (except drummers who use the ER-25). All music teachers should be wearing the ER-15 and some school boards pay for their teachers to get these.www.atlantafest.com/Uggs-Black-Friday.php.

Thank you Marshall.  Dr. Gallert,  there you have it.  For $12.95 children should be wearing the Etymotic HiFi earplugs while taking or practicing their music. Their instructors should be wearing a custom hearing protector (like a dB Blocker Sweet Tones) fitted with an ER15 Etymotic Research flat attenuation filter.  As a side benefit to all of this, your children are learning to protect their precious hearing at an earlier age.  And while we’re talking about age, HiFi earplugs are available in a number of sizes to fit any age, even you old time rockers.Uggs Black Friday.

Ya gots ta learn ‘em

December 1, 2010

I think my grade school English is failing me.  That said, part of the problem  with many relationships today is the lack of balance. For a relationship to work, both parties must be actively engaged in it.  And it isn’t always smooth or harmonious. In fact, when the relationship becomes “energetic” both parties know that each other is engaged.Uggs Black Friday.

What’s this got to do with ears and hearing protection. Everything.  For a hearing conservation program to work both parties, the associate and the employer, must be engaged in it.  Too often, the employer is engaged in a process of fulfilling their responsibilities under the prevailing rules and legislation,  and the associate is engaged in trying to manage their work and private lives.  Does it have to be this way?

In the U.S., under the rules of OSHA (Occupational Health and Safety Administration) there is a program called the Volunteer Protection Programs Participants Association (VPPPA).  This group approaches industrial health and safety differently. In VPPPA companies there is engagement throughout the organization. Sitting on the VPPPA committee are management and associates from all levels in the organization.  There is engagement in VPPPA companies.Uggs Black Friday Deals.

What’s all of this to do with the title? In order to engage associates they need to understand the issues. Only when they understand can they form decisions about how much or how little this affects them.  But this education must be willingly accepted.  To gain acceptance, try accessing some of the education from outside the company.  Not Invented here (hear) is more readily assimilated than what might be perceived as corporate dogma.  For this reason, we offer free hearing conservation workshops to anyone who wants them.  We think that letting employees understand what dangers they face regarding their hearing and the probable outcomes is the first step to them being engaged in the hearing conservation program.Black Friday Ugg Boots