Email sent to EPA contractor Bill Battye of EC/R from Meade Killion of
Etymotic

Tuesday, May 23, 2006

19:33 p.m. 

Bill

 

Thanks for your cheerful response to my inquiry as to why the government
would start out by sending me 21 pages explaining how you plan to keep
my secrets in confidence.  Is this like the DOD losing 27 million
veteran's names and SS numbers into the hands of criminals?  I have no
confidence in any confidentiality that takes 21 pages to describe.  I
prefer a simple assurance, and I assume you will try to keep it and --
as in the DOD actions -- someone in your group may fail.

 

I have a deep seated concern about the tradition of government to take a
bad situation and make it worse, but I choose to hope that this one will
be an exception. 

 

With regard to your questions as to market share, as far as I know
Etymotic Research makes all of the Musicians Earplugs worldwide.  The
finished product, attenuator buttons we produce, custom earmolds earmold
laboratories and audiologist's services run perhaps $170.  E-A-R and
Etymotic Research make all HiFi earplugs as far as we know. These sell
for $12, less in quantity.   Both products are patented.

 

Etymotic Research does not make any non-high-fidelity earplugs. 
Actually, AEARO does sell a high-fidelity earplug patented 20+ years ago
by Ross Gardner:  A yellow foam E-A-R plug deeply inserted is also high
fidelity, giving a fairly flat 40 dB attenuation.  Perfect for heavy
metal rock bands and their listeners.  A colleague recently attended a 
Slipknot heavy-metal rock concert at The Electric Factory in
Philadelphia, where the band played a steady 116 dbA.  Two hours of such
music should produce 300x the allowable daily dose, and cost by my
estimation 150 hair cells.  

 

Those situations are relatively rare, fortunately.  The bad situation in
hearing protection is that some 80-90% of those who need protection need
less than 10 dB, yet the NRR rating on the earplugs they need is so low
that they can't be sold into the application.  As a result, they figure
out how to put high-attenuation foam plugs in improperly or drill holes
in their earmuffs.  Virtually no one needs a 40 dB (NRR=29 dB) earplug
except to prevent being bothered by snoring, a heavy metal rock band, or
extreme noise on an aircraft carrier.  Forcing someone who needs 7 dB to
wear a 40 dB earplug simply encourages them to learn how to circumvent
their excellent performance.

 

My thoughts on the crazy situation created by the use of NRR, and my
suggestion that it should only be used in conjunction with a new ARR
(Audibility Reduction Rating) are found in the Parwum Bonum, Plus Melius
article at the URL below.  

 

A plug with true well-fitted attenuation of 40 dB will usually have an
NRR of 29 dB and my suggested ARR of 51 dB.  Someone with a 20 dB
hearing loss would have a worst-case audibility reduction to a plugged
threshold of 71 dB -- a severe hearing loss.  No wonder people put them
in sideways, especially those with hearing loss already. 

 

http://www.etymotic.com/pdf/erl-0093-1993.pdf

 

A couple of examples:  Etymotic's ER-9 Musicians Earplugs, which give
almost exactly 9 dB to all users,  should perhaps be the earmold of
choice for the vast majority of those needing hearing protection. 
Nonetheless, in one study they received an NRR approaching zero as I
recall.  Similarly, the ER-9 can not be sold as hearing protection in
Europe, where nothing less than their equivalent of NRR = 11 dB is
allowed to be labeled as such.  Probably no ER-9 wearer has obtained
less than 7 dB average attenuation.

 

In another example, in one EARCAL measurement of the one-size-fits-most
HiFi earplug that E-A-R and Etymotic Research both produce and sell, the
average attenuation measured by Elliott Berger on 10 subjects with three
replications was 20.0 dB.  The average of all data at measurement
frequencies of 250 through 8000 Hz was 20 dB.

 

The calculated NRR was 12 dB, and so that number is listed on all
packages by both companies.  The irony is that the not one of the ten
subjects exhibited an across-frequency average attenuation (averaging
their data at all three replications) of less than 19 dB.

 

Those across-frequency average attenuations for the ten subjects were:

20

19

20

20

20

20

20

19

20

19

 

Labeling the package containing such earplugs with NRR = 12 dB is
essentially dishonest:  

 

The problem with the NRR is that it mixes measurement variability with
across-subject variability.  It has long been my belief that it was a
very poorly thought out well-meaning attempt to insure that no one was
cheated of their labeled attenuation.  The problem with this approach is
that anyone can drill holes in their earmuffs if they want.

 

It seems to me we should be able to label the package of HiFi Earplugs 

 

NR = 19-20 dB with proper insertion, and 2-12 dB with improper
insertion.  

 

By providing useful information for the first time, we might take the
burden off of the government and place it on the shoulders of the user,
who is ultimately the only one who can decide how careful to be.  No
one, not even the government, can force someone against his or her will
to properly insert an earplug.  I gather the A method and B method are
moving in that direction, but I suspect they will fall far short of
telling the buyer the truth such as expressed above.

 

I am not inclined to provide any marketing information to the government
so the cost to industry of new labeling can be assessed.  The very
question concerns me, because it misses the real cost:  In my opinion,
the cost of re-labeling would be trivial compared to the human cost of
the present system, which often causes the very hearing loss it is
intended to prevent by: 

    a)  Misrating the low-attenuation earplugs most people need

    b)  Preventing them from even obtaining them as earplugs in Europe

    c)  Pretending that a single government-approved NRR number provides
sufficient information on the basis of which an intelligent consumer
would be induced to choose and use proper protection

    d) Encouraging them to drill holes in their muffs and put the
earplugs in sideways.

 

As such, any cost to Etymotic Research is essentially trivial, given our
mission of preventing hearing loss.  In my view, time after time the
essentially dishonest NRR information has stood in the way of
accomplishing our mission and your mission.

 

Thanks for listening.

 

 

 

Mead C. Killion, Ph.D.,Sc.D.(hon)

   Adjunct Professor of Audiology, Northwestern University 

   Adjunct Professor of Audiology, City University of New York Graduate
School

President, Etymotic Research

