US3506981A - Noise absorbing earmuffs - Google Patents

Description

April 21, 1970 K. c. STEWART ETAL 3,506,981

' NOISE ABSORBING EARMUFFS Filed May 29, 1968 mvsmons Kenneth C. Stewart 8| Ernest J Burgi W United States Patent 3,506,981 NOISE ABSORBING EARMUFFS Kenneth C. Stewart, 344 Bellwalt Drive, McGran Hills,

Bridgeville, Pa. 15017, and Ernest J. Burgi, Box 291-A, RD. 21, 'Cheswick, Pa. 15024 Filed May 29, 1968, Ser. No. 733,051 Int. Cl. A42b 1/06 U.S. Cl. 2-209 4 Claims ABSTRACT OF THE DISCLOSURE A noise attenuating earmuff structure is provided comprising a pair of muffs connected together by a headband by a compliant means, said earmuffs including a cylindrical portion open at one end and closed at the other by a hemispheric member and containing an acoustical attenuating material.

This invention relates to noise absorbing earmuffs and particularly to a pair of spaced earmuffs isolated from a common headband by a connecting resilient member.

Earmuffs for noise suppression and absorption are. commonly used in various occupations where the noise level is high, e.g. at airports, particularly near jet engines and jet prop engines. A completely satisfactory earmuff has not heretofore been produced. So far as we have been able to ascertain, all of the earmuffs presently available suffer from a common defect, namely that they cannot reduce the noise level to a point where it is not annoying. We have found that this minimum level below which prior art earmuffs have been unable to go is the result of a combination of three factors which are (1) failure to isolate the portion of the earmuffs which contact the wearers head from the headband, (2) failure of the muff to seal at its edge against the head of the wearer and (3) inadequacy of sound absorbing material in the muff.

We have discovered a noise absorbing earmuff structure which solves these problems of the prior art and makes possible the substantially complete elimination of noise passage into the ear' of the wearer. We have found that one of the important factors in reducing noise level through such earmuffs is the isolation of that portion of the muff which contacts the wearers head from the headband by means of a compliant member. We have also found that the provision of an acoustic filter between the [muff and the wearers head markedly improves the noise reduction. We have also found that noise reduction can be improved by the design and configuration of each earmuff and the filler thereon. We have found that each of the foregoing mentioned improvements taken alone will markedly increase the noise attenuation of earmuffs and that combined together they provide a noise attenuating earmuff which is vastly superior to any now known to us.

Preferably we provide a pair of muffs connected together by a headband, each of said muffs including a cylindrical body portion open at one end and closed by a hemispherical portion at the other end, an acoustical attenuating material in each said cylinder having portion at the open end adapted to receive a wearers ear, a resilient member surrounding the open end adapted to bear on a wearers head and compliant means separating said body portion and said headband. Preferably the cylinder body is longer than the radius of the hemispherical cap. The compliant material separating the headband and the open end of the cylinder is preferably a resilient member such as an elastomer mass or a spring. The resilient member surrounding the open end of the cylinder is preferably a channel shaped resilient member, the legs of which channel contact the wearers face and form a cavity therebetween which provides an acoustical seal. Preferably each of the muffs is freely movable with respect to the headband so 3,506,981 Patented Apr. 21, 1970 that the band may be used over the head or behind the head as desired by the wearer.

In the foregoing general description of our invention we have set out certain objects, advantages and purposes to be attained thereby. Other objects, purposes and advantages of this invention will be apparent from a consideration of the following description and the accompanying drawings in which:

FIGURE 1 is an isometric view of a pair of earmuffs and connecting headband according to our invention;

FIGURE 2 is a section through a preferred embodiment of noise attenuating earmuff structure according to FIGURE 1 of our invention;

FIGURE 3 is a section through a second embodiment of noise attenuating earmuff structure according to our invention;

FIGURE 4 is a section through a third embodiment of noise attenuating earmuff structure according to our invention; and

FIGURE 5 is a section through a fourth embodiment of noise attenuating earmuff structure according to our invention.

Referring to the drawings and particularly to FIGURE 1 we have illustrated a pair of earmuffs having a cylindrical body portion closed at one end by a hemispherical cap 11 and open at the other end 12 to fit over a wearers ear. A radially outstanding flange 14 surrounds the open end 12 and is provided with a resilient channel member 15 cemented thereto or removably held in place by a snap ring 16- engaging flange 14. The legs 15a and 15b of the channel member 15 engage the head of the wearer and form an annular void 17 therebetween which acts as an acoustical filter. The interior of the body portion is filled with a foamed noise attenuation mass 18 leaving only an ear receiving void 19 at the opening of the body portion. The noise attenuation mass 18 is preferably a foamed elastomer mass of low volume stiffness. A compliant member 20 in the form of a wound spring member extends over the cap 11 and is frictionally movable in a trackway 21 on flange 14 by means of friction rollers 22 on each end of said spring member. A headband 23 is connected to each of two such spring members and muffs to form a complete noise attenuating earmuff structure.

In the embodiment shown in FIGURE 3 we have illustrated a pair of earmuffs each having a cylindrical body portion which is shorter in length than that of FIG- URE 1 and somewhat less effective but still far superior than the prior art structures. Again one end of the body portion 30 is closed by a hemispherical cap 31 at one end and open at the other end 32 to receive the ear of a wearer. The open end 32 is provided with a radially outwardly extending flange 33 carrying a resilient channel member 34 identical with member 15 of FIGURE 1. The body portion interior is filled with a porous noise attenuation mass 35 of low volume stiffness. Each of the earmuffs is connected to a headband 36 by means of a coil spring 37 which acts as the compliant means separating the headband from the earmuff. The spring 37 is rotatable in socket 38 in each of the hemispherical caps 31 so that the headband can be rotated to various positions on the wearers head without removing the earmuffs.

In FIGURE 4 we have illustrated a third embodiment in which a cylindrical head engaging portion 40 is connected at one end to a main body 41 and cap 41a by means of a compliant member 42 in the form of an elastomer ring (rubber, neoprene, butyl rubber, etc.) 43. The interior of the body portion 41 and cap 41a are filled with a porous mass of low volume stiffness 44 as in FIG- URES 1 and 2 leaving only a void 45 to receive the wearers ear. A head engaging channel member 46 is attached to the open end of the head engaging portion 40.

3 The channel member 46 is the same as member 15 of FIGURE 1 and operates in the same fashion to form a noise attenuating Woid 47. The head engaging portions 40 are connected by a headband 48.

In FIGURE we have illustrated a fourth embodiment of our invention in which a cylindrical body portion 50 is closed at one end by a cap 51 and is provided at the other end with an outwardly extending radial flange 52 carrying a head engaging sealing member 53 substantially identical with that identified by the numeral 15 in FIG- URE 1. The body portion is substantially filled with a porous mass 54 of low volume stillness with only a void 55 at the open end to receive a wearers ear. The body portion is provided with a generally spherical socket 56 receiving a foam sphere 57 on one end of a headband 58. The sphere 57 acts as a compliant member to insulate the headband from the body portion.

We claim:

1. A noise attenuating earmuif structure comprising a pair of muffs, a headband connecting said mufis, each of said muffs including a cylindrical body portion open at one end, a hemispherical portion at the other end of said body closing said body, an acoustical attenuating material in each said cylinder having a portion at the open end adapted to receive a wearers ear, a resilient member surrounding the open end adapted to bear on a wearers head and compliant means spacing said body portion from said headband.

2. An earmufl? structure as claimed in claim 1 wherein the compliant means is a spring.

3. An earmuff structure as claimed in claim 1 wherein the compliant means is a resilient member.

4. An earmuff structure as claimed in claim 1 wherein the resilient member surrounding the open end is in the form of a channel opening away from the body portion.

References Cited 1/1936 France.

MERVIN STEIN, Primary Examiner G. H. KRIZMANICH, Assistant Examiner

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