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12) What types of earplugs or other hearing protection are available?




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This article is from the Tinnitus FAQ, by markb@cccd.edu (Mark Bixby) with numerous contributions by others.

12) What types of earplugs or other hearing protection are available?

Wearing ear plugs protects your ears from new damage as well as allowing
them to rest without external stimuli. Noise attenuation may vary by
frequency, so if you're a musician you may want to shop around for ear
protection with fairly flat frequency response. Hearing protection devices
are assigned Noise Reduction Ratings (NRRs) by their manufacturers under
laboratory conditions and may not reflect Real World performance. Most
plugs average around 20dB of noise reduction. Maximal noise reduction
(about 50dB NRR) can be achieved by wearing canal plugs in combination with
muffs, but *some* noise will still be perceived via bone conduction of the
skull in extremely loud situations. The following classes of hearing
protection devices are available:

* moldable ear canal plugs

Moldable ear plugs come in foam, silicone, and wax and fit into the
ear canal itself. Because they are moldable, a tight fit is always
obtained. These are the best hearing protection devices available
today, with NRRs ranging from 15-33dB. Cheap, available in drugstores,
and reusable.

* custom ear plugs

These plugs are made from impressions taken of the customer's ear
canal. NRRs range from 27-29dB, with the cost typically US$30-70. You
generally order these through a hearing specialist who will take the
impressions.

* filtered musician's ear plugs

A variation on custom plugs that offer even sound attenuation across a
broad spectrum of frequencies. NRRs range from 15-20dB, and cost
ranges from US$50-150. A contributor offers this review for one
popular brand:

Now for my 2 cents worth. I am an acoustic engineer working
for the British Broadcasting Corporation (BBC). Although my
main job is designing studios, I also act as a consultant on
noise at work legislation. In that capacity I work on the
safety of people listening professionally on earphones and
loudspeakers, and also musicians in the several orchestras
which the BBC maintains. So I am interested in such items as
musicians earplugs.

We intend to conduct, in the near future, a trial of the
filtered musicians' earplugs that you refer to, and I can
therefore fill out a bit of information on these. The ones
we intend to use are type ER15 from Etymotic Research. These
have an attenuation of 15dB, largely independent of
frequency. (As far as I can find out, these are the only
plugs claiming "flat attenuation" for which independent lab
reports of attenuation are available. Of course you must
have such a report if you're going to use the plugs for
industrial safety purposes.)

Etymotic Research (they like to pronounce the "o" long, as
in rose, by the way, and print it with a line over the top,
but I think they're fighting a losing battle on this one)
also make a non-individually moulded "constant attenuation"
plug, the ER20. However a close examination of its
attenuation vs. frequency characteristic shows that it is
really not all that different from more ordinary plugs.
Despite this, some musicians report finding it useful. Its
overwhelming advantage is that it comes at about 10UKP per
pair!

I can confirm the address you give for Etymotic Research.
They are probably the best people to approach for details of
suppliers in the American continent, as they will be up to
date with changes.

In the UK, the distributor is:

MBS Medical Ltd
129 Southdown Road
Harpenden
Herts. AL5 1PU
England
+44 (0)1582 767007 voice
+44 (0)1582 767214 fax
This is a fairly recent change of supplier.
Cost in the UK - about 120UKP per pair.

The main distributor for Europe is in Holland:
Elcea BV
PO box 230
5100 AE Dongen
The Netherlands
+31 (0) 1623-18480

A large scale research programme on the use of flat
attenuation earplugs with the Dutch Philharmonic Orchestra
has recently been carried out by Dr Van Hees of Amsterdam
University. I believe the findings will be made public soon,
and I will post you if they are relevant.

I have had a pair of these ER15 plugs moulded for myself, to
see what it's like both having the moulds made and wearing
them. The ears must first be checked for wax, which must be
dissolved out in the usual way if excessive. Soft putty-like
material is then put in the ears to make the mould. This is
slightly uncomfortable, but certainly not painful. The
moulds are then sent away to have the plugs made. For
Europe, the plug manufacture is done by Elcea in Holland,
who have a special apparatus for determining when the hole
is the correct diameter. The filters are small flat devices
which clip on to the outside of the plugs. The plugs are
reasonably comfortable in use, although my own ear canals
are very narrow and most earplugs don't fit me well. To give
the flattest attenuation characteristic, the plugs go
somewhat deeper into the ear than an ordinary hearing-aid
earpiece.

Early reports indicate that although their attenuation is
less than that of other plugs, it is still too much for some
musicians. It is possible that a lower attenuation plug will
be available in future.

Although my own work with musicians mainly involves symphony
orchestras, musicians who work on stage in shows and rock
concerts are probably at higher risk, due to high levels of
sound from "foldback" loudspeakers. Listening using small
in-ear earphones (which may possibly be individually
moulded) can reduce the required foldback sound level, as
the earphones keep out a lot of the external sound.

Systems:

Etymotic Research make high quality (but expensive)
earphones which may be used for this purpose - type ER4.

A well known system of this type, usually using a radio link
to the performer, is The Radio Station. Manufacturer:

Garwood Communications
Ltd 8A Hassop Rd
Cricklewood
London NW2 6RX
England
+44 (0) 181 452 4635 voice
+44 (0) 181 452 6974 fax

No doubt I have gone on about some of my pet subjects at
excessive length, but I hope you may find something useful
here. I must, of course, say that my views are entirely my
own and must not be quoted as the BBC's.

* ear muffs

These over the ear devices are more comfortable than canal plugs, and
have NRRs that range from 23-29dB. But they are very bulky and
obviously can't be worn discretely.

* active sportsman's ear muffs

These are active (possibly amplifying), powered devices that pass
normal levels of sound, but will attenuate extremely loud impulse-type
noises similar to gunshots, etc. They are typically sold through gun
catalogs and sporting goods stores, and when used in combination with
plugs can achieve near-maximal NRRs of about 50dB.

Note that amplified muffs actually have a negative NRR, which is one
indication that the NRR doesn't tell the whole story for "impulse"
noise such as gunshots. These muffs detect impulse noise and turn off
the amplification in time to keep that noise from reaching the ear
through the electronics. See below for a first-hand account of active
muff performance:

Date: 16 Apr 1992 8:36 EDT
Subject: Re: electronic muffs

Having just purchased a set of Peltor Tactical 7-S active
muffs from Dillon Precision, I'll add my two cents to the
conversation.

The T7-S's are stereo electronic muffs with a microphone on
the front of each ear cup. They seem to be pretty sturdy in
construction. One cup contains a circuit board covered with
surface-mount parts and some trim pots. The other contains a
nine-volt battery accessible from an outside door (there may
also be a small circuit board in there, too). Each contains
a small speaker, and the two are connected via a cable that
crosses through the headband. There is a single gain control
that is switched to provide the on/off function.
Side-to-side balance is adjustable by one of the trim pots.
A small concern I have is that the foam mic covers may come
to harm while being jostled around in my range bag.

I had originally thought (from where, I don't know) that the
circuit amplified sound according to the gain control, and
shut off completely noises above 85dB. In fact, the unit
never actually shuts down, or if it does the switching is so
quick and quiet that it gets lost in the muffled sounds
coming through the muff's cups. There is constant
compression, so that soft sounds are boosted, and loud
sounds are limited to 85dB or less. The effect is strange at
first, because you don't think there's much muffling being
done, but believe me, you can find out real quick that the
things work very well indeed.

I used the muffs at an outdoor .22 silhouette match, then
later in the day at a large indoor range where we were
shooting .45 ACP and light .44 mag loads. At the match, they
worked great. I could hear the spotters, the range officer,
and all the others. I really didn't have a problem with
distractions as another poster stated. The only "problem" I
had was that at high gain I could easily hear the road noise
of cars and trucks passing by about a quarter-mile away. The
muffs seem to preserve directional information, since I
don't remember having any problems locating sounds (like the
CLANK when a ram fell over 100 yards away).

The indoor range seemed a little different. Gunshots sounded
a bit more veiled, whereas outdoors they just sounded lower
in intensity. Voices were still easy to hear, but also
sounded funny, so it was probably the echo in the large
room. For grins, I tried the T7-S's at the indoor range
without turning the active circuitry on, and swapped back
and forth between them and some Silencio Magnum CDS-80
passive muffs (rated at -29dB -- my previous regular muffs).
In an inactive state, the TS-7's were at least as effective
as the Silencios. Further, the sound of the shots was
perceived as being about an octave lower through the
inactive T7-S's than through the Silencios. This was much
more pleasant over the long run. In fact, my buddy, who was
also wearing CDS-80's, said that his ears were starting to
hurt by the end of our indoor range time. Mine were fine.
(BTW, said buddy tried the T7-S's for a few minutes at each
place -- he's ordering his today.)

I tried sitting in a very quiet room with the muffs turned
way up. I could hear my dog breathing in another room, and
ripples on the surface of a small, nearby aquarium sounded
like a set of river rapids. I could hear my own breathing
quite clearly, and the cloth of my shirt rustling as it rose
and fell. At really high gain, there was some whitish noise
that was either the residual noise of the amplifiers, or the
movement of air in the room.

The muffs are very comfortable. I wore them most of the day
with no problem. The ear seals are soft yet firm, and are
probably more comfortable than the Magnum CDS-80's. The
seals and inner foam pads are easily removable and
replaceable. The rather sparse instruction manual suggests
replacing them once or twice a year for hygienic reasons.

All in all, I really like these muffs. It would be difficult
to go back to passive protection after being able to hear
"normally" while shooting. Dillon currently has the T7-S's
on sale for $129.95. Regular price is $170. I have no
connection with Dillon or Peltor save being a satisfied
customer.

And an addendum to the above account:

Date: 5 Jul 1994 13:39 EDT
Subject: Re: muffs review

The battery should be a nine-volt alkaline, and it will
probably last 10-30 hours (depending on gain setting used)
before you'll notice a drop in volume. I have used the muffs
while mowing (with a gasoline-powered mower), and with noisy
power tools (like a circular saw), and they really help.
Your ears do get a bit warm and sweaty on a hot day,
however. Finally, I have seen pictures of new(?) Peltor
muffs on which the foam mic covers were replaced by hard
plastic grids. These might be an improvement.

Some hearing protection vendors:

Westone Labs
P.O. Box 15100
Colorado Springs, CO 80935
USA
+1 800 525 5071 URL- http://www.earmold.com/

Sells custom plugs.

Dillon Precision Products
7442 E. Butherus Drive
Scottsdale, AZ 85260-2415
USA
+1 800 762 3845 for Catalog requests
+1 800 223 4570 for Sales

Praised on rec.guns have been the "Max" earplugs and Peltor Ultimate 10
muffs. Dillon's "stealth" catalog, The Blue Press is available at no charge

Etymotic Research
61 Martin Lane
Elk Grove, IL 60007
USA
+1 708 228 0006 voice
+1 708 228 6836 fax

Sells musician's earplugs offering about 15dB of flat attenuation.

*****[product #, price, manufacturer, phone number, NRRs?]*****



 

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