Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Title: EARPLUGS
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Field nf the InventiQn
The present invention relates broadly to earplug~ and ~
more specifically directed to a resilient polymeric multiple
flange earplu~ construction useful as a heariny protector.
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In the United State~ one of,the better known earplugs of the
general type contemplated by the present invention i~ that known
as the "V-51 R", the construction details of which earplug are
disclosed in a report entitled ~evelopmen~ of,an_~xtra Small and
Extra Large Size for the V-51 ~ Ea~plug, D. T. Blackstock and 9.
Æ. Von Gierke, April 195~, Aero Medical Laboratory, Wright Air
Development Center~ Air Research and Development Command, United
States ~ir Force~ WADC Technical Report 56-142. This earplug
was developed during the course of World War II in order to
provide improved hearing protection to memb~r8 of the military
who are ~ubjected to concussive sounds, ~uch aæ gunfire or
explosions or to extremely noi~y work environment~, ~uch as at
airports or aircraft maintenance facilitiesO ~he V-5,1~R earplug
is composed of a resilient elastomer;c material, such as
neoprene rubber, and comprises a single retroverted flange
element extending from the nose end of a tubular rubber stalk
member~ The flange element extends rearwardly f rom the nose of
the tubular rubber stalk and is so spaced theref rom as to
provide a free annular space therebet~een. In use, the earplug
is forceably inserted into the ear canal, thereby at least
partially collapsing the rearwardly extending ~lange element
into the underlying free annulàr ~pace and conforming said
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~lange element into an acoustic sealing relationship with the
constraining wall~ of the ear canalO
In U.S. Patent No. 2,427,66,4r J. Y. Dunbar and J. S. Knight,
~eptember 23, 1947 and U.S. Patent No. 2~717,596, J. S. ~ight,
September 13, 1955, there are disclosed earplugs similar to the
V-51 R earplug described in the aforementioned Blackstock et al.
report. In Figures 2 and 3 of U. S. Patent No~ ~,427,664, there
is additionally depicted an earplug comprising four disk-shaped
flange elements of serially increa~ing diameters extending
substantially transversely of the supporting stalk member. As
is most clearly seen in Figure 3~ all ~our flanye elements of
the construction are disclosed to be insertable into the ear
canal and are biased somewhat rearwardly by the constraining
walls thereof~
Unfortunately, earplugs of the type disclo~ed in the
foregoing publications and in those varianks thereo~ known to
the present applicant are of ten possessed of several
disadvantages. Firstly, when properly worn a certain
significant proportion of the wearar population often
experiences discomfort in the use o~ such plugsO Generally this
discomfort is perceived as a sense of excessive pressure being
brought to bear on the walls of the ear canals, which pressure
can be of such magnitude as to be painful. A common user
response to such di scom~ort is to withdraw the offending earplug
from the ear canal to the point where the perceived exce~sive
pressure is relieved and, when this is done~ as often as not the
acoustic seal between the plug and the eax canal is broken 9r
weakened, thereby destro~ing or at least compromising the
intended Aearing protection fl~nction ~f the earplug. This is a
particularly pernicious deficien~y because, while the sub~ect
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person involved may seem from outward appearances to be suitably
hearing protected in fact, he or she may not be protected at
all. Secondly, due to the well known anatomic variability of
sizes and shapes of ear canals throughout the population,
including the variabilit~ which often exi8t8 a~ between the ear
canals of an individual user and the variations in 8iZ e of
individual ear canals which occur naturally, it is generally
required that flanged earplugs be produced in a number of size~
and that they be carefully fitted by trained pe~sonnel in order
~o to as~ure the attainment o~ competent hearing protect1on. For
instance, the V-51 R plug mentioned above is presently produced
in five different di~crete size~ whlch, according to the
a~orementioned Blackstock et al~ report, provides the ability to
properly fit 80-85% of the adult male user population
: 15 therewith. Obviously, the requirement to produce multiple ~izes
of an earplug adds greatly to the cost and complexity of
manufacture thereof. In accordance with the pr~sent invention,
however, there is provided a multiple flange earplug which can
be produced in a single si~e and yet com~ortably fit and provide
effective hearing protection for the great majority of the
population.
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Objects of~h~ I~Yention
It is a principal object of khe present invention to provide
a new and novel multiple flange earplog.
: 25 It is another obj ect oiE the invention at once to provide a
novel multiple ~lange earplug con~truction which is comfortable
to wear properly and which provides competent acoustic sealing
o~ the ear canals.
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It is still another object of the invention to provide a
novel multiple flange earplug con~truction which may be produced
in a single size and which earplug will properly and comfortably
fit up to 98~ of the entire adult user population.
It is still another object of the invention to provide a
novel multiple flange earplug construction wherein the flange
elements may be readily manipul.ated to expose normally hidden
portions of the earplug ~uch as for purposes of cleansing
thereof.
Other objects and advanfages of the present invention will
in part be obvious and will in part appear hereinafter.
In accordance with the invention there is provided a
multiple flange earplug composed of a resilient soft
polymeric material, said earplug comprising a stalk member
carrying thereon an array of at least three hollow
rearwardly directed and spaced apart flange elements of
substantially circular cross ~ections, the first o~ which
elements extends from the nose end of t~e s~alk member~
; 20 Each of the flange elements of ~he array comprises a skirt
of relatively thin uniform thickness and is compo~ed of a
soft resilient polymeric material having a Shore A
:~ Durometer hardness value of between about 10 and abou~ 90
The flange elements of the array increase serially in
diamelter, ~tarting from the nose end o the stalk member,
The diameter of the stalk member underlying each flange
element is selected to provide an annulaL f ree ~pace
. ~ between the inner surface oiE the ski rt of the
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associated flange element and the stalk member of ~uf~icient
dimension as to allow said skirt portion to collapse into and
occupy said space upon in~ertion of the earplug into the ear
canal.
Bri~f Descri~tion of the ~L~
The drawing forming part hereof is a schematic~ diagrammatic
longitudinal sectional view o~ ,an earplug in accordance with the
invention, including various preferred embodiments thereof.
Reference being made to the drawing hereof, the earplug of
the invention broadly comprises a stalk member 1 and an arra~ of
at least three rearwardly oriented and spaced apart flange
elements 10, 20 and 30, each being o~ generally circular cross
section. Preferably, each flange element of the array extends
rearwardly from its point of attachment to the stalk member 1 in
a convexly arcuate manner and, most preferably, will be of
generally hemispherical conformationO By "generally
hemispherical" it is meant that the flange element deflnes no
less than about 45% and no more than about 55% of a chordally
sectioned hollow spherical body whose external surface is, at
essentially all points thereon, substantially equidistant from
its single geometric center. The earplug of the invention can
be fabricated by any suitable polymer molding technique~ such as
by injeotion molding thereof. An essential to the attainment of
the benef its of the invention is the selection of the resilient
polymeric material utilized in the fabrication of at least the
skirts 12, 22 and 3Z o~ flange element~ 10, 20 and 30. Said
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material should have a Shore A Durometer hardness value (by the
technique of ASTM ~240-81) of be~ween about 10 and about 90 and,
preferably, of between about 30 and about 60. The stalk member
1 can, of course, be composed of a resilient polymeric material
of the same type employed for thle flange skirts 12, 22 and 32
elements or, if desired, can be composed of a resilient
polymeric material having a somewhat higher Shore A Durometer
hardness value of, say, up to about 100. In one preferred
embodiment of the invention, he material of construction of the
stalk member 1 will have a Shore A Durometer hardness value of
between about 50 and about 70. In another pre~erred embodiment
of the inven~ion, however, for purpose~ of ea~y fabrication, lt
will be preferred to utili~e a single polymeric material for the
entirety of the constructivn.
Obviously, there are many known resilient polymeric
materials which may be utiliz~d effectively in the fabrica~ion
of the earplugs of the invention. For instance, natural rubber,
neoprene rubber, SBR rubber, silicone rubber, EPDM rubber,
polybutadiene rubber/ polyurethane elastomers, ethylene vinyl
acetate elastomer~, elastomers based on acrylic acid precursors
and vin~l halide polymers are all generally suitable materials
of construction which can generally be procured from commercial
sources with the necessary Shore A Durometer values or whlch can
be suitably compounded (such as by internal and~or external
plasticizing thereof) so as to confer the necessary hardness
values thereto. Particularly preferred polymeric materials are
the thermoplastic silicone rubber compositions such as
exemplified by a family of thermoplastic injection moldable
elastomers sold under the trademark, C-FL~ ~, Concept Polymer
Technolo~ies, Inc., Clearwater, Florida ~hese ~ilicone rubber
compositions are available in a considerable range of Shore A
Durometer hardness values, can be thermally formed into
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intricate shapes by any conventional thermoplastic moldiny
technique and the wares produced there~rom can generally be
sterili~ed or cleansed without degradation thereo~. Another
preferred materlal of construction of the earplug~ of the
invention is a thermoplastic SBR block copolymer such as
produced and ~old in a number of grades under the trade marlc,
KRATON, by Shell Chemical Company, Synthetic Rubber Dlvision,
NY, NY.
The first flange element 10 extellds outwardly and rearwardly
froM the nose end 3 of stalk member 1, thereby to deEine a
uni~ormly thin skirt 12 which is 3paced apart along its length
from that portion of atalk member 1 lying thereunder. The
second flange element 20 extends outwardly and rearwardly from a
first intermediate location along the length of stalk member 1,
thereby to define a uniformly thin skirt 22 which 1~ spaced
apart along its length from that portion o~ stalk member 1 lying
thereunder. Similarly, the third ~lange element 30 extends
outwardly and rearwardly from a second intermediate location
along the length of stalk member 1, thereby to define a
uniformly thin skirt 32 which is spaced apart along its length
from that portion o~ stalk member 1 lying thereunder. AS w111
be noted from the drawin~, the root portions 16, 26 and 36 of
flange skirts 12, 22 and 32 respectively, ln other words, the
points of junature of the interior ~urfaces of said skirts with
the stalk member 1, are preferably con~ormed such a~ to provide
minimum radiusing therebetween, consistent with good molding
practices, thereb~ to mlnimize thickening and consequential
stif~ening of the material of construction at said points. This
design feature of the construction not only assures that the
skirt~ 12, 22 and 32 are afforded maximum flexibility at said
root portions, but also provides the skirts 12, 22 and 32 with a
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desirable "over center" eversion capability whereby each skirt
can be readily manipulated 80 as to be everted ~rom its normally
rearwardly directed orientation to a forwardly directed
orientation. When so forwardly everted, the interior ~urfaces
of said skirts and the portions of the stalk member 1 normally
underlying said skirts are expolsed, thereby affording the user
with the ability to readily inspect and/or cleanse areas o~ the
earplug normally hidden from viewO
It is also to be noted that the diameters of the hollow
flange elements 10, 20 and 30 increase ~erially and that, in a
preferred embodiment of the invention, said elements are spaced
along the length of stalk member 1 such that, in the finished
earplug, a single stra~ght line of construction, L, can be drawn
so as to be in at least point contact with all flange elementæ
of the array. In this pr~ferred embodiment, said diameters and
~pacing are also selected such that the half-angle 0 defined
between said line of construction L and the forwardly extended
centerline CL of the stalk member 1 will re~ide within the
range of between 10 and 16, the preferred range for the
half-angle e being between about 12 and about 14~ By
adherence to these dimensional criteria it i8 a~sured that the
earplug constructed in accordance therewith will be utilizable
by and effective for the great majority of the user population.
For instance~ where the half-angle ~ is 13, the flange
elements are generally hemispherical and the radiu~ of the first
flange element 10 is about 0.165 inch (4.19mm), it has been
found that the earplug of the invention can produce acoustically
: effective seal for up to 98% of the entire adult user
population, including females~
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It will be apparent to those of skill ln the art that many
of the functional benefits of the present invention arise, at
least in part, because the flange elements of the con~truction
are embued with the ability to r~esiliently deform, ln use, to
the extent necessary under relatively small and e~sentilly
linear forc~s exert~d by or refl~ected into the walls of the ear
canal upon inserton of the ea~pl~g thereinto. Thus, there
exists a complex interplay betwe~en the specific geometries and
sizing of the elements of the ea,rplug construction taken in
combination with the hardness(es) of the resilient polymeric
material(s) of construction employed therefor. Accordingly, it
i9 not only important that the material of construction employed
for each of the skirts 12~ 22 and 32 have a Shore A Durometer
hardness value of between about 10 and about 90, but it is also
important that the thickness of each o~ said skirts 12, 22 and
32 fall within the range of from about 0.003 (0.20 mm) and about
0.050 inch (1.27 mm)~ While no hard and fast rule of
construction can be ~et in this regard, generally speaking the
softer the material of construction the greater can be the
thickness o~ the skirt 12, 22 or 32. Where materials of
construction fallin~ within the preferred range of Shore A
Durometer hardness value~ of between about 30 and about 60 are
employed, it has been found that the benefits of the invention
are gen4rally substantially forthcoming when the thickness uf
each of the skirts 12, 22 and 32 is within the range of 0.030
inch ~0.76 mm) and 0DO12 inch (0.30 mm~. Obviously/ the proper
balancing of thickness of each of the sklrts 12, 22 and 32 and
the Shore A Durometer hardness value of the resilient polymeric
material of construction thereof can be readily determined
experimentally. In a pr~ferred embodiment of the invention, it
has been found that a nominal thickness of about 0~020 inch
(0.50 mm) of each of the skirts 12, 22 and 32 and the use
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therefor of a resilient polymeric material of construction
having a Shore A Durometer har~ness value of about 40 yields an
earplug construction having an excellent overall combination of
effective acoustic sealing and wearer comfort propertiesr
As mentioned previously, the diameter of that portion of the
stalk member underlying each of the skirts 12, 22 and 32 of the
: flange elements 1~, 20 and 30, respectively, is selected such as
to provide an annular free spac:e 11, 21 or 31 thereunder and
into which free space said skirt i~ enabled to deflect during
insertion of the earplug ~nto the ear canal. The specific
dimensions of the annular free spaces 11, 21 and 31 are not
particularly critical provided~ of course, that each be adequate
to serve the ~oregoing function. It is, however, ~enerally
desirable that each said annular free space have a dimen~ion
thereacross, determined by subtracting the diameter of $he
underlying stalk member f rom the internal diameter of the open
end of the skirt and dividing the result by two, of at least
twice the thickness of the particular ~kirt 1~, 22, or 32
disposed thereover. By ~annular free ~pace", it is meant that
2~ the annular space 11, 21 or 31 contain no element or material
therein which would tend to obstruct or restrict ~he movement of
the as~ocia~ed skirt thereinto.
Bearing the foregoing in mind, it is within the ambi~ of the
invention to form the stalk member 1 of a single uni~orm
diameter. Where this is done, however~ it will be obvious that
due consideration of the annular f ree space underlying each
: flange skirt will ordinarily dictate that the uniform diameter
selected for the stalk member 1 will be based up~n consideration
of the annular free space for the smallest skirt, ln other
words, the skirt 12 of the nose flange element lOo Thus~ unless
the contemplated constant diameter stalk member is formed ~rom a
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relatively stiff resilient polymeric material, ~ch as one
having a Shore A Durometer hardness value of greater than about
50, it can be found that the re~ulting earplug construction can
be somewhat flaccid along the stalk member 1 and that ~aid stalk
member does not provide ~ufficient support for the ~econd and
third flange element~ 20 and 30 as to permit them to be readily
inserted into the ear canal solely by manipulation oP the ~talk
member. For these rea~ons, then, ~t is generally preferred that
the diameter of the ~talk member 1, particularly where it i8
formed of a matexial of construction having a Shore A Durometer
; hardness value of less than about 50, be progresslvely or
serially increased rearwardly from flan~e element to flange
: el~ment, thereby to progressively or serially stiffen that
portion of said member supporting the flan~e el~ments thereon~
In order tha the earplugs of the invention can be readily
inserted and removed f rom the ear canal, it is desirable that
the stalk member 1 extend rearwardly to any convenient length
beyond the trailing edge 34 of the rearmost flange elemen 30
such that the rearmost portion thereof defines a handle 42 to
be readily grasped between the thumb and forefinger o~ the
user.
It is often desirable to provide pairs of ~arplugs tethered
together by means of a length of pliant cord~ Such a tethered
earplug construction can serve to prevent accidential dropping
or loss thereof. This can be of importance~ for lnstance, where
the earplugs are to be utilized in an industrial food processin~
environment or in an environment wherein a dropped earplug would
be likely to be so dirtied as to be rendered unusable or to be
lost altogether. In order to provide such a tethered earplug
constructionr the ~ree end 40 of stalk member 1 can be provided
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with an axially oriented channel or aperture 41 of a ~ize
adapted to receive the end of a length of a pliant cord (not
shown) therein. Said cord can be ~ecured in the channel or
aperture 41 by any suitable means, such as ~y solvent or thermal
welding thereof or by use of a suitable adhesive or b~ use of a
cord whose ends are of somewhat greater diameter than the
diameter of the receiving ~hannel or aperture 41, thereby to
cau~e the resilient polymeric material surrounding said channel
or aperture 41 to resiliently grasp the cord ends in a secure
manner. For further general detail~ relating to tethered
earplug constructions reference may be had to ~uch literature
as: U.S. Patent No. D-241,881~ to Peterson et alO ~ u. s. Patent
No. 4,193,396, to Wacker; U~S. Patent No. 4,219,018, to Draper,
Jr.; U.S. Patent No. D~245,202, to Asker~
Additionally, while earplugs in accordance with the present
invention may, as hereinbefore indicated, be utilized as
individual ear insertable wares, they may also be utilized as
stopple elements of a hearing protector device comprising a
generally U-shaped spring headband to the ~ree ends of whicb
headband the ~topple elements are affixed in an inwardly
directed manner. In this embodiment, the earplugs of the
invention are inserted into the ear canals of the wearer and are
maintained under the continuous inwardly directed biasing forc~s
. of the spring headband. Further detail relatlng to hearing
protectors of this general type can be had by reference to such
lit~rature as U.S. Patent No. 4,461,290, to Gardner, JrO et al.,
or U.K. Patent Ilo. 1,355,052, to Metal Box Company, Limi~ed.
Utiliz ing the foregoing principles of construction and for
illustrative, non-limiting exemplary purposes, a plurality o~
three-flange earplugs substantially conformin~ to the drawing
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hereof was produced by injection molding of a thermoplastic
silicone rubber (C-FLE ~ elastomer) havLng a Shor~ A Duro~neter
hardness value of about 40. Referring to the drawing, the
dimensions of the earplugs so produced are set forth below:
Overall length of ~talk member 1 1.183 inches (30.05~n)
Diameter of stalk member 1 at end 40 0~203 inch ( 5.15mm~
Diameter of stalk member 1 ~nderlying
skirt 32 0.203 inch ( 5.1Smm)
Diameter of stalk member 1 underlylng
skirt 22 0~188 inch ( 4.78mm)
Diamete r of stalk member 1 underlying
skirt 12 0.134 inch ~ 3~40mm)
Radius of hemispherical flange element
10 0.165 inch ( 4.19mm)
Radius of hemispherical flange element
~o 0~203 inch ( 5.15mm)
Radius of hemispherical flange element
30 Or255 inch ( 6.48mm)
Axial length of hemispherical flange element
10 0.174 inch ( 4.42mm)
Axial length of hemispherical flange element
20 0.206 inch ( 5~23mm)
Axial length of hemispherical flange element
0.262 inch ( 6.65mm~
Thickness of skirts 12, 22 and 32,
each 0.019 inch ( 0~48mm)
Length~ nose 3 to nose 24 0.385 inch ( 9~78mm)
Length, nose 3 to nose 34 0~649 inch ~16.48mm)
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Annular space 11 0.085 inch ( 2.16mm)
Annular ~:pace 21 t).090 inch ( 2.28mm)
Annular space 31 0.135 lnch ( 3.43mm)
Half-angle ~ 13
~he earplugs were tested in accordance with the test
procedure of ANSI S3.19-1974, utilizing ten ~ubjects. In the
first test series (hereinafter "l~aximum Comfort Testn) 'che
subiects were instructed to insert the plugs into their ear
canals only to the point of maxim-~m perceived wearer comfort.
In the second test series (hereinafter "Maximllm Attenuation
Testn) the subjects were individually fitted by a trained
technician to the point of maximum acoustic sealing of the ear
canals by the plugs. ~he Maximum Comfort Test yielded an NRR
value of 22 wh~le the Maximum Attenuation ~est yielded an NRR
value of 25., During the course of the Maximum Comfort Test the
subj ects were asked to assess the relative comfort of the f itted
earplugs in accordance with the following scale:
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HEARING PROTECTIVE DEVICE COMFORT RATING SCALE
Comfortable Comfortable Und~scided Uncomfortable Painful
O 1 2 3 4 5 6 . . _ _ ~ g 10
The average comfort rating afforded the earplugs of the
invention by the test subjects was about 3.
For comparative purposes, a similar test serie~ was
carried out with the same cadre of te~t subjects utilizing a
commercially available multiple flange earpl~g of the prior
art. The Maximum Comfort ~est yielded an NRR value of only 16.
: The ~aximum Attenua~ion Test yielded an N~R value of about 23
The average comfort rating afforded these commercial.earplugs by
the test subjects durin9 the course of the Maximum Comfort Test
was about 4. --
Another Maximum Comfort Test was carried out with the same
cadre of test subjects utilizing yet another commercially
available multiple flange earplug of the prior art. The NRR
value was about 13 and the average comfort rating accorded the
earplugs was about 6.
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Slnce many embodiments, modifications and variations of the
present invention may be made in view of the ~bove teachings
without departing from the spir.it of the invention, it will be
understood that, within the ~cope of the appended claims, the
invention may be practiced othe.rwise than as specifically
described here~nbefore.
What is claimed is:
