US3922721A

US3922721A - Wearable sound attenuating enclosure

Info

Publication number: US3922721A
Application number: US507825A
Authority: US
Inventors: Robert S Gales; Robert S Harrah
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1974-09-20
Filing date: 1974-09-20
Publication date: 1975-12-02
Anticipated expiration: 1992-12-02

Abstract

A lightweight noise attenuating enclosure is shaped to cover the head, neck and upper thorax. A rigid outer shell and a sound attenuation layer block up to ten db of ambient noise and a number of pads mounted along the mouth of the enclosure prevents the bypass of noise. Thusly fabricated, the enclosure is ideally suited to allow work site audiometry testing for the hearing loss caused by noisy machinery. An opening in the front wall of the enclosure allows oral and visual communications without overly compromising the enclosure''s attenuation capabilities.

Description

x12 3 ,a22, 721 j l? I ifl United States 1 1 3,922,721

Gales et al. t;

[ 1 WEARABLE SOUND ATTENUATING ENCLOSURE Inventors: Robert S. Gales, San Diego; Robert S. Harrah, La .lolla, both of Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

[22] Filed: Sept. 20, 1974 [21] Appl. No.: 507,825

[52] US. Cl 2/2 R; 2/209; 181/33 R [51] Int. Cl. G10K 11/04 [58] Field of Search 2/209, 2 R, 3 R, 205, 171, 2/202, 6; 181/33 R, 33 K, 33 C; 179/183, 156 R [56] References Cited UNITED STATES PATENTS 3,021,914 2/1962 Wilson 181/33 K 3,088,002 4/1963 Heisig 2/6 X 3,237,713 3/1966 Leslie 179/183 X 3,244,816 4/1966 Karns 181/33 K 3,423,763 1/1969 Schwartz 2/171 Dec. 2, 1975 3,621,488 11/1971 Gales 2/6 3,707,004 12/1972 3,828,888 8/1974 Gottschalk 181/33 R FOREIGN PATENTS OR APPLICATIONS 554,273 6/1957 ltaly 181/33 K Primary Examiner-Werner H. Schroeder Assistant ExaminerPeter Nerbun Attorney, Agent, or Firm-Richard S. Sciascia; Ervin F. Johnston; Thomas Glenn Keough [57] ABSTRACT A lightweight noise attenuating enclosure is shaped to cover the head, neck and upper thorax. A rigid outer shell and a sound attenuation layer block up to ten db of ambient noise and a number of pads mounted along the mouth of the enclosure prevents the bypass of noise. Thusly fabricated, the enclosure is ideally suited to allow work site audiometry testing for the hearing loss caused by noisy machinery. An opening in the front wall of the enclosure allows oral and visual communications without overly compromising the enclosures attenuation capabilities.

3 Claims, 4 Drawing Figures US. Patent Dec. 2, 1975 f6 hi 2 l I. 1w 2 a 2.

H... w. w. 4

FlG.l'

WEARABLE SOUND ATTENUATING ENCLOSURE STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Many methods and devices are used to reduce or prevent bearing damage in high noise environments. Se-

lecting the proper acoustic barrier to be interposed in the path between the noise source and the eardrums has presented problems however. Certain high noise sources can be neutralized by one type of earplug while another noise source may be blocked by another earmuff-type barrier. A safety engineer first must analyze the noise source or its effects on individuals near the source and then prescribe the proper barrier. The analysis most often consists of testing individuals who have recently been in the high noise environment. By well known audiometry techniques the hearing losses at different frequencies are identified. Usually, the testing procedure was performed at a distant acoustically dampened laboratory. During the time it took to get to the laboratory, a partial restoration of the hearing loss inevitably occurred. Thus, the results of the audiometry test were inconclusive with respect to the actual hearing damage suffered on the job. The safety engineers and technicians needed to administer the hearing test as soon as possible after exposure to the noise source so that conclusive results could be obtained. Industrial I safety engineers long have searched for a technique or device by which audiograms would be acquired soon near the high noise environment.

SUMMARY OF THE INVENTION The invention is directed to providing an apparatus for ensuring a degree of acoustic isolation from impinging noise. A rigid shell and laminated layer of sound absorbing material are fashioned and dimensioned to define a cavity for enclosing the head, neck and upper thorax in a spaced relationship. A sealing means in the form of several pads reach across the upper thorax, the back and across the shoulders to block any noise bypass. Since the materials chosen are relatively lightweight, the apparatus is completely portable and capable of accompanying audiometry technicians outside of the laboratory to perform a real-time testing of personnel exposed to a high noise source. Up to ten decibels of impinging acoustic energy is attenuated by this apparatus to ensure amore responsive audio test.

It is a prime object to the invention to provide a noise attenuation head gear.

It is another object to the invention to provide a device for ensuring a more representative audio test.

It is a further object to the invention to provide a portable device allowing an audio test at or near a high noise environment.

Another object is to provide an apparatus which can supplement conventional earplug or earmuff acoustic barriers.

Yet another object is to provide a device which blocks noise from impinging on the head, neck, thorax and upper back of the test individual.

Still another object is to provide an on-site noise attenuation enclosure which allows oral and visual communications.

These and other objects of the invention will become more readily apparent from the ensuing specification when taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric depiction of the invention.

FIG. 2 is a cross-sectional representation of the invention taken generally along lines 2'2 in FIG. 1.

FIG. 3 is a cross-sectional representation of the invention taken generally along lines 33 in FIG. 1.

FIG. 4 shows a variation in the noise attenuating laminate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings,'thereis shown a representative design of the noise attenuation enclosure 10 as an individual is undergoing a hearing test. The noise attenuation enclosure includes a top portion 11 which is essentially dome-shaped and has a sufficient radius of curvature to maintain a spaced relationship from the test subjects head. Depending from the domeshaped top portion, a back portion 12, extends downwardly in a slightly outwardly flaring configuration to terminate in a lower part 12a. This part is suitably shaped to reach across and lie on the upper part of the shoulders.

On opposite sides, a pair of

side portions

13 and 14 extend downwardly from the dome-shaped top portion to form the lateral confines of the enclosure, such confines being dimensioned to be a spaced distance from a subject undergoing an audiometer test. The lower extremes of the side portions are shaped to define a pair of

shoulder portions

15 and 16 which have rounded contours for accommodating the upper surfaces of the shoulders.

Lastly, a front portion 17 of the attenuation enclosure depends in a slight outwardly flaring shape and a lower part 17a is configured to conform to the surface of the upper thorax. Optionally, an opening 18 is included in the front portion to enable visual and audio communications. The opening is relatively small so as not to overly compromise the enclosures attenuation capabilities, while giving a degree of communication with the technicians administering the audiometric test.

A plastic or a rubber strip 19 is bonded onto the lip of cavity defined by the afordescribed portions to protect the enclosure and the test subjects from being scratched or cut by the otherwise exposed rim of the enclosure.

The constituent portions making up the enclosure are integrally formed. Any of many well-known molding processes or extrusion techniques are drawn upon to give shape to the enclosure. Irrespective of exactly what mode is chosen, the enclosure must have a sufficient structural strength to remain intact after a good many tests.

A laminated enclosure has proven to be rugged and lightweight yet provides the desired attenuation. A single outer shell 20, is made from fibrous glass impregnated with resin and cured. Forming this shell to an approximately one-eighth inch thickness is well within the state-of-the-art and elaboration thereon is unnecessary. If desired, a plastic or a metal shell can be substituted,

however, such materials tend to be either fragile or excessively heavy for the planned use. Bonded onto the inner walls of the shell is a noise absorption layer 21. The layer is about one-half an inch thick and is selected from a number of materials, such as fibrous glass, cork granuales, sponge rubber, plastic foam or other suitable equivalents which are covered by a porus cloth, when needed.

The acoustic cooperation of the shell and layer are such as to provide a ten decibel attenuation of impinging noise. The shell reflects a portion of the incoming energy and the absoption layer diffuses a portion of the impinging energy which has been transmitted through the shell. In order to ensure that the cavity enclosed by the portions is acoustically isolated to the minus decibel level,

shoulder pads

22 and 23 and front and rear pads 24 and 25 are mounted around the mouth of the enclosure. Sponge rubber has been found to be a suitable material although some resilient plastic foams have also been used with a degree of success. Irrespective of the type of material chosen, the compliant nature of the pads and their sound absorptive property help acoustically seal the interior of the enclosure from the outside.

There is evidence to suggest that repeated exposures to a high energy noise source eventually result in permanent damage. At first the exposures to the noise source produce only a temporary, recoverable loss of hearing. After a relatively short period of time, normal hearing was restored. Heretofore, testing for hearing loss called for an individuals being transported a good distance to a sound test lab. When the test was administered, it was usually some time after the test subject was in the high noise environment. As a result, there would be a partial recovery of the hearing lost and the test would not show the temporary hearing damage suffered.

The present invention allows an immediate hearing analysis. A relatively quiet room, such as an off ce at the factory, is suitable for conducting a hearing test. Since the office is only five to ten minutes at the most removed from thenoise source, a true indication of hearing loss will be obtained.

The test subject is seated comfortably. A head set 26 having a pair of speakers coupled by a wire 27 to an audiometer, is placed over the ears. Next, noise attenuation enclosure 10 is fitted over the head, to cover the head, neck and upper thorax. Now, the hearing test begins and is completed before any partial recovery of the hearing loss occurs. An accurate representative indication of hearing loss is provided for safety engineers to allow corrective action.

After this test is completed, the enclosure is removed and another subject can be tested. Usually the subsequent tests can be given without any modification of the enclosure. Thicker or

thinner pads

23, 24, 25 and 26 are changed if needed to seal the cavity.

In the embodiment thusly described, an enclosure having a shell of no more than one-eighth of an inch thick of the fibrous glass impregnated with resinand noise absoption layer of not more than one-half inch of plastic foam effected a ten decibel attenuation of impinging noise. An even greater degree of attenuation is provided when several shells 28 andnoise absorbing layers 29 are laminated, see FIG. 4. Admittedly, there is a weight increase, however there is also a corresponding increase in the attenuation level.

Other modifications, not shown in the drawings are the inclusion of a flexible sleeve reaching between opening 18 and the test subjects face. A transparent faceplate may be added along with a breathing duct. The sleeve faceplate and tube provide additional attenuation with no sacrifice in the communication capability. I

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings, and, it is therefore understood that within the scope of the disclosed inventive concept, the invention may be practiced otherwise than specifically described.

What is claimed is:

1. An apparatus for ensuring a high degree of acoustic isolation from impinging noise in a high noise environment comprising:

a rigid .shell having a dome-shaped top portion, downwardly reaching front, back and side portions and a pair of shoulder portions each outwardly extending from a separate oneof the side portions, all the portions are integrally formed, shaped with rounded contours which are dimensioned to define a cavity for enclosing the head, neck and upper thorax in a spaced relationship; and the front portion is provided with an opening for permitting visual and oral communication, yet being of a small enough size so as not to overly compromise ambient noise attenuation;

at least one layer of a sound absorbing material mounted on the inner surfaces of the aforestated portions; and 7 means carried on the mouth of the cavity between the shell and the shoulders, the chest and the back for sealing the cavity shut except for the small opening in the front portion for sealing out impinging noise when said apparatus is placed to enclose the head, neck and upper thorax, the

rigid shell, sound absorbing layer and sealing means are selected from materials which are sufficiently lightweight to permit portability and which acoustically cooperate to provide a ten db ambient noise attenuation.

2. An apparatus according to claim 1 in which the rigid shell is fibrous glass bonded'with resin and the sound absorbing layer is plastic foam.

3. An apparatus according to claim 1 in which the rigid shell is optionally fibrous glass bonded with resin and plastic and metal and the sound absorbing layer is optionally fibrous glass and cellulose fiber and plastic foam each covered with a porous cloth.

Claims

1. An apparatus for ensuring a high degree of acoustic isolation from impinging noise in a high noise environment comprising: a rigid shell having a dome-shaped top portion, downwardly reaching front, back and side portions and a pair of shoulder portions each outwardly extending from a separate one of the side portions, all the portions are integrally formed, shaped with rounded contours which are dimensioned to define a cavity for enclosing the head, neck and upper thorax in a spaced relationship; and the front portion is provided with an opening for permitting visual and oral communication, yet being of a small enough size so as not to overly compromise ambient noise attenuation; at least one layer of a sound absorbing material mounted on the inner surfaces of the aforestated portions; and means carried on the mouth of the cavity between the shell and the shoulders, the chest and the back for sealing the cavity shut except for the small opening in the front portion for sealing out impinging noise when said apparatus is placed to enclose the head, neck and upper thorax, the rigid shell, sound absorbing layer and sealing means are selected from materials which are sufficiently lightweight to permit portability and which acoustically cooperate to provide a ten db ambient noise attenuation.

2. An apparatus according to claim 1 in which the rigid shell is fibrous glass bonded with resin and the sound absorbing layer is plastic foam.