SE463847B - EARN PROPERTY OF ELASTIC POLYMER MATERIAL - Google Patents

Description

463 847 2 earplugs of the type described in the above-mentioned publications and in known variants thereof are unfortunately often encumbered with several disadvantages. First, when such plugs are worn correctly, a significant proportion of individuals often experience discomfort when using the plugs. This discomfort is perceived as a feeling of excessive pressure on the walls of the ear canal. which pressure can be of such strength that it is painful. The usual reaction to such discomfort is that the individual removes the earplug from the ear canal to a position where the perceived strong pressure eases and once this is done the acoustic seal between the earplug and the ear canal is broken or weakened. whereby the intended hearing protection function of the earplug has been lost or at least deteriorated. This is a particularly pernicious shortcoming. because from the outside it may seem as if the person in question has appropriate hearing protection but he or she is in fact not protected at all. Due to the well-known anatomical variation in the size and shape of the ear canals in different individuals and that variation. which are often present between the ear canals of individual users and the variations in the size of individual ear canals that are naturally present. Secondly, it is necessary to produce collared earplugs in a number of sizes and that they must be carefully fitted by these personnel to ensure the achievement of correct hearing protection.

For example, the above-mentioned earplug V-51 R is currently produced in five different sizes. which according to the above report by Blackstock et al. provides the opportunity to appropriately provide 80-85% of all adult male individuals with it. The need to produce many sizes of an earplug obviously contributes greatly to the cost and the intricate manufacture thereof. According to the present invention, however, a multi-collar earplug is provided. which can be produced in a single size and yet fit comfortably and provide effective hearing protection for the majority of the population.

A main object of the invention is to provide a new multi-collar earplug. 8117 4 :.

CN C: I Another object of the invention is to provide a new multi-collar earplug construction which is comfortable to wear correctly and which provides good acoustic sealing of the ear canals.

A further object of the invention is to provide a new multi-collar earplug construction, which can be manufactured in a single size and which earplug correctly and comfortably fits up to 98% of all adult individuals. Yet another object of the invention is to provide a new multi-collar earplug structure in which the collar members can be flexibly manipulated to expose normally hidden portions of the earplug, such as for the purpose of cleaning the same.

Other objects and advantages of the invention are in part obvious and will in part be set forth in the following.

According to the invention, there is provided an earplug of elastically polymeric material, comprising an elongate stem portion having a front end, a collar assembly comprising at least three hollow, rearwardly directed collar members having substantially circular cross-sections and successively increasing diameter and formed integrally with the stem portion at spaced intervals along at least a part of its length, the collar element with the smallest diameter being located at said front end, and characterized by the features which appear from claim 1. The diameter of the stem part below each collar element is chosen so that a free annular gap is found between the inside of the collar in the collar element in question and the stem part with sufficient dimension for said collar part to be able to sink into and occupy the space in said gap when the earplug is inserted into the ear canal.

Attached drawing figure shows schematically. diagrammatically in longitudinal section an earplug according to the invention. Referring to the drawing figure, the earplug according to the invention consists of a stem part 1 and a set of at least three rearwardly oriented and spaced collar elements 10, 20 and 30. each with a substantially circular cross section.

Each collar element in the set preferably extends backwards from its point of contact with the stem part 1 in a convex arcuate manner and preferably has a substantially hemispherical shape. Heath "substantially hemispherical" means that the collar member defines no less than about 45% and no more than about 55% of a cord-sectioned hollow spherical body whose outside at substantially all points thereon is substantially equidistant from its only geometric center. The earplug of the invention can be made by any suitable polymer forming technique. such as by injection molding. Essential in achieving the advantages of the invention is the choice of the elastic polymeric material used in the manufacture of at least the collars 12, 22 and 36 of the collar elements 10, 20 and 30. This material shall have a Shore A Durometer hardness (according to the technique in ASTM 2240). 81) of between about 10 and about 90 and preferably between about and about 60. The stem part 1 may of course be composed of an elastic polymeric material of the same type used for the collars 12, 22 and 32 or may if desired be composed of an elastic polymeric material having a slightly higher Shore A Durometer hardness of say up to about 100. According to a preferred embodiment of the invention, the construction material in the stem part 1 has a Shore A Durometer hardness of between about 50 and about 70. According to another preferred embodiment of the invention however, for ease of manufacture, it is preferred to use a single polymeric material for the entire structure.

There are many known elastic polymeric materials which can be used successfully in the manufacture of the earplugs according to the invention. For example, natural rubber, neoprene rubber.

SBR rubber. silicone rubber. EPDH rubber. polybutadiene rubber, polyurethane elastomer. ethylene-vinyl acetate elastomers, elastomers based on acrylic acid precursors and vinyl halide polymers all generally suitable construction materials, which can be obtained on the market with the required Shore A Durometer values or s 465 847 which can be mixed together in a suitable manner (such as with internal and / or external plasticizers therefor ) to achieve the necessary hardness. Particularly preferred polymeric materials are thermoplastic silicone rubber compositions such as, for example, a family of thermoplastic injection moldable elastomers sold under the tradename "C-FLEX", Concept Polymer Technologies.

Inc .. Clearwater. Florida, USA. These silicone rubber compositions are available in a variety of Shore A hardnesses. can be thermally formed into intricate shapes by any conventional thermoplastic molding technique and articles made therefrom can generally be sterilized or cleaned without degradation. Another preferred construction material for the earplugs of the invention is a thermoplastic SBR block copolymer, such as that manufactured and sold in a number of grades under the tradename "KRATON" by Shell Chemical Company, Synthetic Rubber Division, NY, NY, USA.

The first collar element 10 extends outwards and backwards from the front end 3 of the stem part 1 and thereby delimits a uniformly thin collar 12. which along its length is separated from the part of the stem part 1 which lies below it. The second collar element 20 extends outwards and backwards from a first intermediate position along the length of the stem part 1 and thereby delimits a uniformly thin collar 22. which along its length is separated from the part of the stem part 1 which lies below it. Likewise, the third collar element 30 extends outwards and backwards from a second intermediate position along the length of the stem part 1 and thereby delimits a uniformly thin collar 32, which along its length is different from the part of the stem part 1 which lies below it. As can be seen from the drawing figure, the bottom portions 16, 26 and 36 of the collars 12, 22 and 32, respectively, in other words the points of intersection of the insides of the collars with the stem part 1 are preferably shaped so that the smallest possible radius of curvature is therebetween for facilitated forming technique. thereby minimizing thickening and concomitant stiffening of the construction material at these points. This design of the construction not only leads to the collars 12, 22 and 32 being given maximum flexibility in said bottom portions but also to GK (_) J that the collars 12, 22 and 32 are given the desired ability to be turned in and out ". over the center ". whereby each collar can be easily caused to be turned in and out from its normally backward orientation to a forward orientation. When the collars are turned in and out forwards, the insides of the collars and the parts of the stem part 1 which normally lie under the collars are exposed outwards, whereby the user can easily inspect and / or clean parts of the earplug which are normally hidden for inspection.

It should also be pointed out that the diameters of the hollow collar elements 10 and 30 increase in order and that according to a preferred embodiment of the invention these elements are arranged at a distance from each other along the length of the stem part 1, so that in the finished earplugs a single straight construction line L can be drawn that is at least in point contact with all collar elements in the set. In this preferred embodiment, the diameters and distances are also chosen so that the half angle 6 defined between the construction line L and the forward center line CL of the stem part 1 will be in the range between 10 and 16 °, the preferred range for the half angle 6 being between about 12 and about 14 °.

By adhering to these dimensional criteria, it is ensured that the earplug designed accordingly will be usable and effective for the vast majority of intended users.

When, for example, the half-angle 6 is 13 °, the collar elements are substantially hemispherical and the radius of the first collar element is about 4.19 mm and it has then been found that the earplug according to the invention can produce acoustically effective seals for up to 98% of all adult individuals including women.

It is obvious to the person skilled in the art that many functional advantages of the invention derive at least in part from the fact that the collar elements in the construction have the ability to be elastically deformed to the required extent under relatively small and substantially linear forces exerted by or directed against the walls of the ear canal. earplugs in it. There is thus a complicated interplay between the specific geometries and the sizes of the elements in the ears.

The plug construction taken in combination with the hardness (s) of the elastic polymeric construction material or materials used therefor. Thus, it is not only important that the construction material used for each of the collars 12, 22 and 32 has a Shore A Durometer hardness of between about 10 and about 90, but it is also important that the thickness of each of the collars 12. 22 and 32 falls in the range of about 0.20 mm and 1.27 mm. Although no specific design rule can be stated in this regard, it generally applies that the softer the construction material, the greater the thickness of the collars 12. 22 or 32. In the case of construction materials which fall within the preferred range for the Shore A Durometer, the hardness of between about 30 and about 60, it has been found that the advantages of the invention generally appear substantially when the thickness of each of the collars 12, 22 and 32 is in the range of 0.76 mm to 0.30 mm. The adapted balancing of the thickness of each of the collars 12. 22 and 32 and the Shore A Durometer hardness of the elastic polymeric construction material in them can, of course, be easily determined experimentally. According to a preferred embodiment of the invention, it has been found that a nominal thickness of about 0.50 mm of each of the collars 12, 22 and 32 and the use of an elastic polymeric construction material with a Shore A Durometer hardness of about 40 gives an earplug construction with an excellent overall combination of effective acoustic sealing properties and means that the wearer finds the earplug comfortable.

As mentioned above, the diameter of the part of the stem part which lies below each of the collars 12, 22 and 32 in the collar elements 10, 20 and 30, respectively, is selected so that a free annular gap 11, 21 or 31 is found below it and in which gap the collar can bends in when the earplug is inserted into the ear canal. The specific dimensions of the free ring gaps ll. 21 and 31 are not particularly critical provided, of course, that each may correctly perform the above function. However, it is generally desirable that each free ring gap have a dimension across it. determined by subtracting the diameter of the underlying stem portion from the inner diameter of the open end of the JJ Ü \ CN Of * _12: * JJ collar and dividing the result by 2. by at least twice the thickness of the specific collar 12, 22 or 32. By "free ring gap" is meant that the ring gap ll. 21 or 31 does not contain elements or materials that could block or restrict the movement of the associated collar into the gap.

In view of the above, it is within the scope of the invention to design the stem part 1 with a single uniform diameter. When this is done, however, it is obvious that due consideration of the free annular gap under each collar dictates that the uniform diameter selected for the stem part 1 is based on consideration of the free annular gap for the smallest collar. i.e. the collar 12 in the front collar element 10. Unless the constant diameter stem part in question is formed by a relatively rigid, elastic. polymeric material. as a material with a Shore A Durometer hardness greater than about 50, it may be found that the resulting earplug structure may be slightly slack along the stem portion 1 and that this stem portion does not provide sufficient support for the second and third collar members 20 and for them to be properly can be inserted into the ear canal only by manipulating the stem part. For these reasons, it is therefore generally preferred that the diameter of the stem part 1, especially when it is formed of a construction material with a Shore A Durometer hardness of less than about 50, gradually increase backwards from collar element to collar element. so that the part of the stem part which supports the collar elements progressively becomes stiffer.

In order for the earplugs according to the invention to be easily inserted into and taken out of the ear canal, it is desirable that the stem part 1 extends backwards to some suitable length behind the rear edge 34 of the rearmost collar element 30. so that the rearmost part defines a handle 42 that can be easily gripped between the thumb and forefinger by the user.

It is often desirable to have pairs of earplugs fastened together using a piece of flexible wire. Such an attached earplug structure can help to prevent the temporary loss or loss of it) Iß ß fl $> Ch ce __) 42: ~ q. This can e.g. be important when the earplugs are to be used in an industrial food processing environment or in an environment where a dropped earplug would become so contaminated that it would become unusable or completely lost. To provide such a fastened earplug structure, the free end 40 of the stem portion 1 may be provided with an axially oriented channel or opening 41 of a size adapted to receive the end of a flexible wire (not shown) therein. This wire may be anchored in the channel or opening 41 in a suitable manner. such as by solution welding or thermal welding thereof or using any suitable adhesive or using a wire. whose ends have a slightly larger diameter than the diameter of the receiving channel or opening 41. whereby the elastic polymeric material surrounding the channel or opening 41 elastically catches the wire ends and locks them. Further details regarding the fastened earplug constructions can be found in the literature such as U.S. Patent No. D-241,881. US-A 4,193,396.

US-A 4,219,018 and U.S. Patent No. D-245,202. Although the earplugs of the invention set forth above may be used individually. earplugs. they can also be used as plugs in a hearing protector comprising a substantially U-shaped resilient headband. to whose free ends the plugs are attached inwards. According to this embodiment, the earplugs according to the invention are inserted into the wearer's ear canals and are retained under continuous inwardly directed forces by the resilient headband. Further details regarding hearing protection of this general type can be obtained with reference to such literature as US-A 4,461,290 and GB-B 1,355,052.

In application of the above design principles and in illustrative. For non-limiting purposes, a number of three-collar earplugs were made substantially in accordance with the drawing figure by injection molding a thermoplastic silicone rubber (C-FLEXå elastomer) having a Shore A Durometer hardness of about 40.

Referring to the drawing figure, the dimensions of the earplugs were as shown below: früš SÅIf / q 10 total length of the stem 1 30.05 mm diameter of the stem l at the end 40 5.15 mm diameter of the stem 1 below the collar 32 5.15 mm diameter of the stem 1 under the collar 22 4.78 mm diameter of the stem 1 under the collar 12 3.40 mm radius of hemispherical collar element 10 4.19 mm radius of hemispherical collar element 20 5.15 mm radius of hemispherical collar element 30 6.48 mm axial length of hemispherical collar element 10 4.42 mm axial length of hemispherical collar element 20 5.23 mm axial length of hemispherical collar element 30 6.65 mm thickness of collars 12. 22 and 32 each 0.48 mm length. tip 3 to tip 24 9.78 mm length. tip 3 to tip 34 16.48 mm ring gap ll 2.16 mm ring gap 21 2.28 mm ring gap 31 3.43 mm half-angle 6 l3 ° earplugs were tested according to the test method in ANSI 53.19-l974 using ten people. In the first series of experiments (called the "Maximum Comfort Test"), the subjects were instructed to insert the plugs into the ear canals only to a position for maximum perceived comfort. In the second series of experiments ("Maximum Attenuation Test"), the plugs were inserted on the subjects by a trained techniques to a position for maximum acoustic sealing of the ear canals. The Maximum Comfort Test gave an NRR value of 22 while the Maximum Attenuation Test gave an NRR value of 25. During the course of the Maximum Comfort Test, the subjects were asked to rate the relative comfort of the fitted earplugs according to the following assessment scale: 'x CN Cad oo ¿_ |' _ '\ \ q ll Convenience assessment scale for hearing protection device Very comfortable Comfortable Doubtful Uncomfortable Painful 0 l 2 3 4 5 6 7 8 9 10 The average assessment value with the earplugs according to the invention in the subjects was about 3.

For comparative purposes, a similar test series was performed with the same subjects using a commercially available multi-collar earplug of known type. At the Maximum Comfort Test, an NRR value of only 16 was obtained. The Maximum Attenuation Test gave an NRR value of about 23. The average comfort rating obtained with these commercial earplugs from the subjects during the Maximum Comfort Test Well Approx. 4.

Another Maximum Comfort Test was performed with the same subjects using another commercially available multi-collar earplug of known type. The NRR value was about 13 and the average comfort rating achieved with the earplugs was about 6.

Because many embodiments. Modifications and variations of the invention may be made in light of the above techniques without departing from the spirit of the invention. it is understood that the invention, within the scope of the appended claims. can be practiced in other ways than those specifically described above.

Claims (17)

10 15 20 25 30 35 12 J? C \ x (bl OC? -P-a \ J Patent claim 1. l. Earplug made of elastic polymeric material. comprising an elongate stem part (1) with a front end (3). a collar set comprising at least three hollow, rearwardly directed collar elements (10, 20, 30) having substantially circular cross-sections and successively increasing diameter and formed integrally with the stem portion (1) at spaced intervals along at least a portion of its length. wherein the collar element (10) with the smallest diameter is located at said front end (3). characterized in that the collar element (10, 20, 30) has a substantially hemispherical shape and comprises a thin collar (12, 22. 32) with a substantially uniform thickness of between about 0.20 mm and about 1.27 mm and which is built up of an elastic polymeric construction material with a Shore A Durometer hardness of between about 10 and about 90. the diameter of each part of said stem part (1) under each collar (12. 22, 32) is such that a free annular gap (ll. 21. 31) is delimited between the inside of the collar (12, 22. 32) and the stem part (l) ._ 2. A plug according to claim 1, characterized in that the distances between the collar elements (10, 20. 30) and their diameters are such that a straight construction line can be drawn. which is in at least point contact with each of the collar elements (10. 20. 30) in the set and that this construction line intersects the forward center line of said stem part (1) and defines a relatively small half angle (0) therebetween. 3. an earplug according to claim 2, characterized in that the half angle (9) is between about 10 and about 16 °. An anxiety plug according to claim 2, characterized in that the half angle (9) is between about 12 and about 14 °. Earplug according to claim 1, characterized in that the construction material 1 each of the collar elements (10, 20, V) 10 15 20 25 30 35 13 A / -7 n A7 “TUJ ULr / 30) in said set has a Shore A Durometer hardness of between about 30 and about 60. An orifice plug according to claim 5, characterized in that the thickness of the collar (12, 22, 32) in each collar element (10, 20. 30) is between about 0.76 mm and about 0.30 mm. 7. An earplug according to claim 1, characterized in that the construction material in each of the collars (12, 22. 32) has a Shore A Durometer hardness of about 40 and that the thickness of the collar is about 0.50 mm. Concern according to claim 1, characterized in that the diameter of each part of the stem part (1) which lies below each collar (12. 22, 32) increases backwards from collar element to collar element. 9. A plug according to claim 8, characterized in that the elastic polymeric construction material in the stem part (1) has a Shore A Durometer hardness of less than about 50. 10. l0. The plug according to claim 1, characterized in that the elastic polymeric construction material in the stem part (1) has a Shore A Durometer hardness of between about 50 and about 70. 11. ll. Ankle plug according to claim 1, characterized in that the dimension across each free ring gap (ll, 21, 31) is at least twice the thickness of the collar (12. 22. 32) connected thereto. An earplug according to claim 1, characterized in that the stem part (1) extends backwards from the last (30) of the collar elements to a sufficient length to delimit a handle (42) with which the earplug can be handled. Earplug according to claim 12, characterized in that the free end (40) of the stem part (1) is constituted by an axially oriented channel (41) of a size adapted to receive therein one end of a piece of a flexible wire functioning as anchor therefore. 10 15 20 25 14 463 847 An earplug according to claim 1, characterized in that the connection point (16, 26. 36) between the inner part of the collar (12, 22. 32) in each collar element (10. 20. 30) in the set and the stem part (1) has the smallest possible radius. whereby the thickness of the construction material at said joining point is minimal and the collar is given the ability to be manually turned in and out into a forward conformation. whereby the inside of the collar and the part of the stem part below it are exposed. 15. An earplug according to claim 1, characterized in that it is composed of thermoplastic silicon rubber. Earplug according to claim 1, characterized in that the mutual distances between the collar elements (10.20.30) having a substantially hemispherical shape along the stem part (1) are such that the trailing edge (14.24.34) of each collar (12.22.32) in each collar element (10.20.30) there is 1 a plane. which at least coincides with a plane through the imaginary nose end of the subsequent collar element (10.20.30). Ankle plug according to claim 1, characterized in that the mutual distances between the collar elements (10.20.30) having a substantially hemispherical shape along the stand part (1) are such that the trailing edge (14.24.34) of each collar (12.22.32) 1 each collar element (10.20.30) seen from the side insignificantly covers the nose end of the subsequent collar element (10.20.30).