US3637040A - Ear defenders - Google Patents

Ear defenders Download PDF

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Publication number
US3637040A
US3637040A US843405A US3637040DA US3637040A US 3637040 A US3637040 A US 3637040A US 843405 A US843405 A US 843405A US 3637040D A US3637040D A US 3637040DA US 3637040 A US3637040 A US 3637040A
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United States
Prior art keywords
shell
air
volume
acoustic
passage means
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US843405A
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English (en)
Inventor
Anthony Graham Gorman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Amplivox Ltd
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Amplivox Ltd
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Filing date
Publication date
Priority claimed from GB2833969A external-priority patent/GB1276498A/en
Application filed by Amplivox Ltd filed Critical Amplivox Ltd
Application granted granted Critical
Publication of US3637040A publication Critical patent/US3637040A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F11/00—Methods or devices for treatment of the ears or hearing sense; Non-electric hearing aids; Methods or devices for enabling ear patients to achieve auditory perception through physiological senses other than hearing sense; Protective devices for the ears, carried on the body or in the hand
    • A61F11/06—Protective devices for the ears
    • A61F11/14—Protective devices for the ears external, e.g. earcaps or earmuffs

Definitions

  • FIG 9 FREQUENCY H /4 7 A 1 ml/f/ C2 M7 1 M2 2 0 C, B P 3 0 H Q OUT FIG /5 FRE UENCY 'INVENTOR ATTORNEY EAR DEFENDERS This invention relates to ear defenders.
  • Ear defender assemblies are frequently an integral part of other head-wom equipment such as protective helmets, and in such cases it is difficult to remove the headgear for the occasions on which the wearer wishes to hear normal airborne sounds.
  • This difficulty has been reduced by arranging a port or ports suitably disposed in the material of the ear defender shell so arranged that the port or ports can be opened or closed at will.
  • the ear defender assembly provides maximum attenuation to airborne sounds andnoises, but when the ports are opened airborne sounds are permitted to reach the wearers ears in a fairly normal manner.
  • an ear defender including a shell of rigid material for enclosing a volume of air around a wearers car, a passage in said shell for sound waves to said volume of air, at least one element providing acoustic impedance between the outside of said ear defender and said passage, said impedance being selected in conjunction with the acoustic impedance of said volume of air so as to constitute therewith an acoustic filter which attenuates at least higher frequency components of sound passing to said wearers ear.
  • FIG. 1 shows a cross-sectional elevation of an embodiment of an ear defender according to the invention
  • FIG. 2 is an end view of said ear defender
  • FIG. 3 is the equivalent electrical circuit to the acoustic circuit of said ear defender
  • FIG. 4 is a frequency response curve for said ear defender
  • FIG. 5 is a cross-sectional elevation of an ear defender in accordance with another embodiment of the invention.
  • FIGS. 6 to 10 are electrical equivalent circuits illustrative of the operation of the invention.
  • FIGS. 11 to 15 are graphs representing the characteristics of the respective electrical equivalent circuits of FIGS. 6 to 10.
  • the member I is a shell of rigid and dense material which can enclose a volume of air around the wearers car (not shown).
  • Member 2 is a sealing annulus whose function is the sealing of the forward annular face of the shell to the side of the wearers head and the elimination of acoustic leaks between the internal volume of the shell and the outside air.
  • Said member 2 consists preferably of a liquid-filled tube, but alternatively it may be filled with some resilient material such as plastic foam.
  • the shell 2 provides a significant degree of attenuation of sound in accordance with known principles.
  • ports 3 are provided, and bearing against the outside face of the rear of the shell 1 is a disc member 4 which possesses ports 5 disposed so as to align with the ports 3 when said disc 4 has a suitably relative disposition with the rear face of the shell 1.
  • Said disc 4 is arranged o be rotatable by means of the axial mounting 6 and thus if the disc 4 is suitably rotated the holes 3 and 5 areno longer in alignment.
  • the disc 4 is covered on its outer face by a disc or pad 7 of suitably porous material such as felt or preferably foamed plastic.
  • Disc 7 which is of suitably chosen material and dimensions constitutes an acoustic resistance. Its purpose is to absorb the acoustic energy in any turbulence which is created when the assembly is present in the path of moving air, for example in windy conditions, and reduce the acoustic noise which would otherwise be produced by such turbulence and which would reach the wearer's ear.
  • the acoustic resistance which is directly in the path of sound waves passing from the outer air into the volume, 20, enclosed by member I and the ear of the wearer constitutes one element of a lowpass filter of the resistance-capacitance type.
  • the capacitive element of said low-pass filter is formed by said air volume 20.
  • Said filter is illustrated in FIG. 3 wherein P represents the input pressure of the system and P represents the output pressure.
  • the frequency response of this filter is illustrated in FIG. 4.
  • the precise value of the effective acoustic resistance in the path of incident sound waves is defined not only by a careful choice of material and dimensions of the disc 7 but also by the size and number of the ports 3 and 5.
  • the acoustic impedance of such a plastic disc can be made suitably small compared with the other acoustic impedances in the system.
  • An outer housing 9 serves the functions of maintaining in close proximity the relevant elements, and of providing a suitable grip for the required rotation of the acoustic valve assembly.
  • a spring member 10 is provided and is arranged to ensure that when the acoustic valve is in the closed position member 4 and the rear face of member 1 are maintained in intimate contact so as to avoid the inlet of sound via any unintentional gap between said member 4 and the rear face of said member 1.
  • a telephone receiver 11 is incorporated in the assembly for the reception of speech or other signals via an electrical communications system.
  • the telephone receiver is so mounted that it does not obstruct the sound path from the outside air to the wearers car when the acoustic valve arrangement is in the open position.
  • a suitable quantity of acoustic absorbent material 12 is incorporated into the volume enclosed by member 1 so as to reduce or effectively eliminate any unwanted acoustic resonances within the volume.
  • FIG. 5 parts similar to those shown in FIG. 1 have the same reference numeral.
  • the construction is similar to that described above with regard to the shell 1, sealing annulus 2, ports 3, disc member 4 and ports 5.
  • Member 15 is an operating means for rotating disc 4, but other means such as, for example, an axially mounted knob, may also be used.
  • the enclosed volume 20 shown in FIG. 1 is represented by a shunt capacitance C by classical analogy.
  • P represents the input pressure of the system and P represents the output pressure. It can be shown that such a system has zero attenuation provided that the source impedance associated with the energy input is small compared with the impedance of the element C and this is the case when we are concerned with the propagation of sound in free air.
  • the response of such a system is shown in FIG. 11.
  • this system will provide an attenuation independent of frequency and of degree dependent upon the relative impedances of C and C according to known principles.
  • the response of such a system is shown in FIG. 12, and in this embodiment the impedance C is realized by the stiffness of the diaphragm 14 shown in FIG. 5. 7
  • the response of the system will be of the form shown in FIG. 13 in which the peak of response occurs at a frequency determined by the impedance of M in conjunction with the combined impedances of C and C It will be appreciated that over a small band of frequencies the attenuation is now zero or may be even less than zero.
  • FIG. 9 an element R, associated with diaphragm 14, but not necessarily so, has been added in order to eliminate the undesirable enhancement of the response of the system shown in FIG. 8.
  • the response of the system shown in FIG. 9 is as shown in FIG. 14. It can be seen that we now have an approach to a band-pass filter. It will nonnally be the case that when the resilience of diaphragm 14 of FIG. has been suitably chose so as to provide the required degree of low-frequency attenuation, and when the mass M, of diaphragm 14 shown in FIG. 5 has been chosen to provide reduction of this attenuation at the chosen frequency, then the higher frequency cutoff of the system will be undesirably low.
  • the frequency range over which there is substantially no attenuation can be suitably chosen to include the range of frequencies which are most important with respect to the intelligible reception of speech, for instance from LOGO-3,000 Hz.
  • the fact that at both lower and higher frequencies there is significant attenuation results in a desirable improvement in signal/noise ratio and intelligibility when the wearer of the ear defender assembly is wishing to listen to speech whilst in a noisy situation.
  • the curve B in FIG. 15 shows the response of the system when the impedance of element C has been increased due to increased air pressures in the environment surrounding the ear defender assembly. It can be seen from a comparison of curves A and B that significant additional attenuation is introduced over a useful frequency range with consequent improved protection of the wearers ears against the explosive loud noises which produce such an increased air pressure.
  • Member 14 is preferably but not necessarily made of a suitable plastics material. It also serves the useful purpose of sealing the acoustic valve assembly against the ingress of moisture and of preventing discomfort to the wearer when the ear defender assembly is used in windy situations.
  • the system reverts to a lowpass filter with characteristics similar to those of the embodiment described with respect to FIG. 1.
  • the diaphragm is forced into a taut condition by increased air pressure due to explosive noises the attenuation is even greater because there was little initial attenuation of the low frequencies.
  • the member 8 is a sheet of polyethylene mounted in a nontaut manner.
  • the complete ear defender assembly may be simply supported on the head by means of a headband or it may be incorporated into a protective helmet such as worn by aircrews and the crews of fighting vehicles.
  • Ear defender apparatus for protecting the ear of a user against undesirable sound, comprising a shell (1) adapted to enclose a first volume of air (20) about the users ear, said shell containing passage means (3) for conducting sound waves to said volume of air;
  • an acoustic impedance element (7, 14) connected with the external surface of said shell across the orifice of said passage means for controlling the transmission of sound to said volume of air through said passage means, said impedance element cooperating with said first volume of air to define an acoustic filter that attenuates at least the higher frequency components of sound that would otherwise pass to the users ear;
  • acoustic valve means (4) arranged between said shell and said impedance element for operation between open and closed positions relative to said passage means, said acoustic valve means including a disc (4) connected for coplanar movement relative to said shell, said disc containing at least one aperture (5) arranged for selective alignment with the orifice of said passage means.
  • acoustic impedance element comprises a diaphragm (14) connected in spaced relation with said shell to define a second volume of air (13) on the opposite side of said passage means from said first volume of air.
  • valve-operating means connected at one end with said disc, said valve-operating means (15) extending through said second volume of air and through an opening contained in said diaphragm.
  • Ear defender means for protecting the ear of a user against undesirable sound, comprising a. a shell (1) adapted to enclose a first volume of air (20) about the users ear, said shell containing passage means (3) for conducting sound waves to said volume of air; and
  • an acoustic impedance element connected with the external surface of said shell across the orifice of said passage means for controlling the transmission of sound to said volume of air through said passage means, said impedance element cooperating with said first volume of air to define an acoustic filter that attenuates at least the higher frequency components of sound that would otherwise pass to the user's ear, said acoustic impedance element comprising 1. a resilient diaphragm (14) having properties of stiffness and mass, and
  • Ear defender means for protecting the ear of a user against undesirable sound, comprising a. a shell (1) adapted to enclose a first volume of air (20) about the users ear, said shell containing passage means (3) for conducting sound waves to said volume of air; b. an acoustic impedance element connected with the external surface of said shell across the orifice of said passage means for controlling the transmission of sound to said volume of air through said passage means, said acoustic impedance element including 1. a resilient diaphragm (14) having properties of stiffness and mass, and
  • acoustic valve means (4) arranged between said shell and said impedance element for operation between open and closed positions relative to said passage means, said acoustic valve means including a disc (4) connected for coplanar movement relative to said shell, said disc containing at least one aperture (5) arranged for selective alignment with the orifice of said passage means.
US843405A 1968-08-01 1969-07-22 Ear defenders Expired - Lifetime US3637040A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB3684268 1968-08-01
GB2833969A GB1276498A (en) 1968-08-01 1968-08-01 Improvements in and relating to ear defenders

Publications (1)

Publication Number Publication Date
US3637040A true US3637040A (en) 1972-01-25

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US843405A Expired - Lifetime US3637040A (en) 1968-08-01 1969-07-22 Ear defenders

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US (1) US3637040A (xx)
CH (1) CH496441A (xx)
DE (1) DE1938259C3 (xx)
FR (1) FR2014846A1 (xx)
NL (1) NL156042B (xx)
SE (1) SE352526B (xx)

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3837681A (en) * 1973-06-28 1974-09-24 W Reynolds Stethoscope
US3934100A (en) * 1974-04-22 1976-01-20 Seeburg Corporation Acoustic coupler for use with auditory equipment
US3938616A (en) * 1973-11-27 1976-02-17 Brownfield Swayze W Sound multiplier
EP0091829A1 (en) * 1982-04-13 1983-10-19 The Marconi Company Limited Ear defenders
EP0092362A2 (en) * 1982-04-19 1983-10-26 Clayton H. Allen Nonlinear passive acoustic filtering
US4459707A (en) * 1982-08-23 1984-07-17 Cabot Corporation Ear protecting device
US4465159A (en) * 1983-03-11 1984-08-14 Cabot Corporation Nonlinear ear protecting device
WO2002080830A1 (en) * 2001-04-09 2002-10-17 Cabot Safety Intermediate Corporation Earmuff with controlled leak
US20030095670A1 (en) * 2000-07-25 2003-05-22 Wurtz Michael Jon Active-noise-reduction headsets with front-cavity venting
US20040125976A1 (en) * 2002-12-30 2004-07-01 Reneker Brian Scott Headphones or earmuffs with a user operated mechanical device that controls the volume of exterior sound entering the ear of the user
US20050008167A1 (en) * 2003-04-30 2005-01-13 Achim Gleissner Device for picking up/reproducing audio signals
US20050283882A1 (en) * 2004-01-23 2005-12-29 Elliott Berger High attenuating earmuff device
US20070253589A1 (en) * 2006-04-26 2007-11-01 Foo Toon J Earphone
US20080123884A1 (en) * 2006-08-22 2008-05-29 David Donenfeld Passive hearing aid device
US20080165981A1 (en) * 2000-07-25 2008-07-10 Michael Jon Wurtz Active-noise-reduction headsets with front-cavity venting
US20090049586A1 (en) * 2007-08-14 2009-02-26 Head Germany, Gmbh Safety helmet
US20110158421A1 (en) * 2009-12-24 2011-06-30 Voix Jeremie In-ear device with selectable frequency response
USD735161S1 (en) * 2013-08-16 2015-07-28 Microsoft Corporation Earcups for a headset
USD735691S1 (en) * 2013-08-16 2015-08-04 Microsoft Corporation Earcups for a headset
USD848396S1 (en) * 2017-11-02 2019-05-14 Honeywell International Inc. Noise monitoring headset
USD864899S1 (en) * 2018-05-11 2019-10-29 Techcool Industry Development Co., Ltd. Headset
USD877714S1 (en) 2018-09-25 2020-03-10 Microsoft Corporation Headset
USD878327S1 (en) 2018-09-25 2020-03-17 Microsoft Corporation Earcups for a headset
US20220168149A1 (en) * 2019-03-21 2022-06-02 Minuendo As Ear protection

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2546355A1 (fr) * 1983-05-19 1984-11-23 Fame Casque de protection et dispositif emetteur de signaux sonores
DE3623315A1 (de) * 1986-07-11 1988-01-21 Wolfgang Brede Kg Vorrichtung fuer einen tiefpass-gehoerschutz

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US125339A (en) * 1872-04-02 Improvement in ear-muffs
US2390794A (en) * 1944-02-21 1945-12-11 Zenith Radio Corp Frequency response control
CH242047A (de) * 1944-05-20 1946-04-15 Luzius Prof Dr Med Rueedi Gerät für den Schutz des Gehörs gegen schädigende Schalleinwirkungen.
US2672864A (en) * 1951-07-18 1954-03-23 Makara Frank Audio mask
US2754365A (en) * 1952-09-15 1956-07-10 Maico Company Inc Acoustical tone control for wearable hearing aids
US2976948A (en) * 1958-01-03 1961-03-28 Canada Nat Res Council Mechanical device for distance discrimination of sounds
US3220505A (en) * 1964-04-01 1965-11-30 Willard B Hargrave Audiometric headset
US3335720A (en) * 1965-06-02 1967-08-15 Leonard Peter Frieder Valve for sound attenuating device

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL78163C (xx) * 1950-05-11
FR1145964A (fr) * 1954-05-20 1957-11-05 Ca Nat Research Council Protège-tympans
GB1183232A (en) * 1966-02-25 1970-03-04 Kahn Leonard R Improvements in or relating to Hearing Protection Systems

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US125339A (en) * 1872-04-02 Improvement in ear-muffs
US2390794A (en) * 1944-02-21 1945-12-11 Zenith Radio Corp Frequency response control
CH242047A (de) * 1944-05-20 1946-04-15 Luzius Prof Dr Med Rueedi Gerät für den Schutz des Gehörs gegen schädigende Schalleinwirkungen.
US2672864A (en) * 1951-07-18 1954-03-23 Makara Frank Audio mask
US2754365A (en) * 1952-09-15 1956-07-10 Maico Company Inc Acoustical tone control for wearable hearing aids
US2976948A (en) * 1958-01-03 1961-03-28 Canada Nat Res Council Mechanical device for distance discrimination of sounds
US3220505A (en) * 1964-04-01 1965-11-30 Willard B Hargrave Audiometric headset
US3335720A (en) * 1965-06-02 1967-08-15 Leonard Peter Frieder Valve for sound attenuating device

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3837681A (en) * 1973-06-28 1974-09-24 W Reynolds Stethoscope
US3938616A (en) * 1973-11-27 1976-02-17 Brownfield Swayze W Sound multiplier
US3934100A (en) * 1974-04-22 1976-01-20 Seeburg Corporation Acoustic coupler for use with auditory equipment
EP0091829A1 (en) * 1982-04-13 1983-10-19 The Marconi Company Limited Ear defenders
EP0092362A2 (en) * 1982-04-19 1983-10-26 Clayton H. Allen Nonlinear passive acoustic filtering
EP0092362A3 (en) * 1982-04-19 1985-11-21 Clayton H. Allen Nonlinear passive acoustic filtering
US4459707A (en) * 1982-08-23 1984-07-17 Cabot Corporation Ear protecting device
US4465159A (en) * 1983-03-11 1984-08-14 Cabot Corporation Nonlinear ear protecting device
US20080165981A1 (en) * 2000-07-25 2008-07-10 Michael Jon Wurtz Active-noise-reduction headsets with front-cavity venting
US20030095670A1 (en) * 2000-07-25 2003-05-22 Wurtz Michael Jon Active-noise-reduction headsets with front-cavity venting
US7317802B2 (en) * 2000-07-25 2008-01-08 Lightspeed Aviation, Inc. Active-noise-reduction headsets with front-cavity venting
WO2002080830A1 (en) * 2001-04-09 2002-10-17 Cabot Safety Intermediate Corporation Earmuff with controlled leak
US6826287B2 (en) 2001-04-09 2004-11-30 Cabot Safety Intermediate Corporation Earmuff with controlled leak
US20040125976A1 (en) * 2002-12-30 2004-07-01 Reneker Brian Scott Headphones or earmuffs with a user operated mechanical device that controls the volume of exterior sound entering the ear of the user
US20050008167A1 (en) * 2003-04-30 2005-01-13 Achim Gleissner Device for picking up/reproducing audio signals
US20050283882A1 (en) * 2004-01-23 2005-12-29 Elliott Berger High attenuating earmuff device
US20070253589A1 (en) * 2006-04-26 2007-11-01 Foo Toon J Earphone
US20080123884A1 (en) * 2006-08-22 2008-05-29 David Donenfeld Passive hearing aid device
US20090049586A1 (en) * 2007-08-14 2009-02-26 Head Germany, Gmbh Safety helmet
US20110158421A1 (en) * 2009-12-24 2011-06-30 Voix Jeremie In-ear device with selectable frequency response
US8903114B2 (en) 2009-12-24 2014-12-02 Sonomax Technologies Inc. In-ear device with selectable frequency response
USD735161S1 (en) * 2013-08-16 2015-07-28 Microsoft Corporation Earcups for a headset
USD735691S1 (en) * 2013-08-16 2015-08-04 Microsoft Corporation Earcups for a headset
USD848396S1 (en) * 2017-11-02 2019-05-14 Honeywell International Inc. Noise monitoring headset
USD864899S1 (en) * 2018-05-11 2019-10-29 Techcool Industry Development Co., Ltd. Headset
USD877714S1 (en) 2018-09-25 2020-03-10 Microsoft Corporation Headset
USD878327S1 (en) 2018-09-25 2020-03-17 Microsoft Corporation Earcups for a headset
US20220168149A1 (en) * 2019-03-21 2022-06-02 Minuendo As Ear protection

Also Published As

Publication number Publication date
NL156042B (nl) 1978-03-15
DE1938259C3 (de) 1974-06-06
DE1938259A1 (de) 1970-02-05
DE1938259B2 (de) 1973-11-08
NL6911432A (xx) 1970-02-03
CH496441A (fr) 1970-09-30
SE352526B (xx) 1973-01-08
FR2014846A1 (xx) 1970-04-24

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