Recommendations for Shooters?

K.R.Catchpole3 at student.lut.ac.uk K.R.Catchpole3 at student.lut.ac.uk
Thu Mar 9 05:08:16 EST 1995


In article <3j26jl$r64 at nntp1.u.washington.edu> basiji at u.washington.edu (David Basiji) writes:
>
>Over in rec.guns, there's been some discussion of the
>most effective forms of hearing protection. The general
>consensus is that people either wear a combination of
>closed-cell foam plugs (e.g. EAR, about 29 dB attenuation)
>and muffs (usually about 25 dB attenuation), or a set
>of heavy muffs with electronically limited built-in 
>microphones to cut off any sound over 80 dB or so.
>The theory is that the plugs stop air conduction while the
>muffs help with bone conduction. The problem is, nobody really
>has a good quantitative estimate of how effective these
>methods are because the industry apparently doesn't use
>impulse noise to test their products. 
>
>Does anyone out there work in impulse noise attenuation?
>I assume that the weighted average method of measuring
>attenuation is also a rough guide to effectiveness with
>impulse noise, but are there any gotchas I should know about?
>Any insight you can provide would be appreciated.
>
>Thanks,
>David Basiji
>UW Bioengineering

I worked for the British Navy last year, and one of the significant parts of
job was to test impulse noise exposure according to a certain defence standard.

Basically it took the peak pressure level for one shot, the B-duration (time
taken for the SPL to reach 1/20 th of the peak, and gave a figure for the 
number of shots one could be exposed to per 24 hours.

In most cases, despite the use of both EAR plugs and earmuffs, (which give a
combined attenuation of about 25 dB) the best way to protect hearing from even
small arms fire was to limit the exposure. 
Protection can only get you so far.

The exposures depend on the weapon, and also very much on where the firing is
done.  The same small arms on an open air range give far higher exposures on
an indoor range.
The safe exposure limit for a rife was about 25 shots per 24 hours, even with
plug and mufff protection.  One or two shots without either exceeded the safe
limit.

Prevention is better than protection.
If you want to shoot, make sure you wear the protection ANYWHERE where you 
might be exposed to shots, whoever is firing.  Exposure from one shot without
protection can do more damage than 20 shots with protection.

Ken.


			#########	You may know what I don't know
>> Ken Catchpole <<	###   ###	But not that I don't know it.
			###   ###	So you will have to tell me everything..
							'Knots' - R D Laing





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