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Publication numberUS2427664 A
Publication typeGrant
Publication dateSep 23, 1947
Filing dateSep 17, 1945
Priority dateSep 17, 1945
Publication numberUS 2427664 A, US 2427664A, US-A-2427664, US2427664 A, US2427664A
InventorsJames Y Dunbar, John S Knight
Original AssigneeJames Y Dunbar, John S Knight
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Hearing guard and ear protector
US 2427664 A
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Description  (OCR text may contain errors)

Sept. 23, 1947. DUNBAR AL 2,427,664

HEARDIG GUARD AND EAR PROTECTOR Filed Sept. 17, 1945 Fig.

damn if Dunbar John S. Knight TAT E HEARING GUARD AND EAR PROTECTOR James Y. Dunbar and John S. Knight, United States Navy Application September 17, 1945, Serial No. 616,942

3 Claims. (Cl. 128151) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention pertains to improvements in tection when acted on by a force of pounds .per hearing guards and especially to a plug for prosquare inch. It has also been found that an tecting the inner ear and contiguous brain secincrease in weight of a lead plug from .005 pound tions from damage due to blast and shock waves, to .020 pound or an increase in weight by 4 times and from excessive sound levels. 5 will decrease the shock only about half. There- The use of hearing guards of rubber, composifore, the weight should be selected for wearing tion, wax, and cotton has long been customary comfort. in an effort to protect the ear mechanism, The Although lead is preferred as the impedance use of modern explosives has rendered these inmass, any heavy mass could be used without deadequate. Attempts have also been mad to filter lo parting from the scop of the invention. The out certain intense sounds and to seal the ears mass should be encased in a holder of rubber. against high pressures without satisfactory neoprene, or any other resilient material formed result. to fit into the outer ear canal. It should be pro- Present records and data show that damage vided with resilient sealing flange or flanges 4 to does not coincide with excess pressures or dural5 prevent irritation and provide a sn fi a tion of pressure alone. Injury in some cases is should preferably be provided with a tab 5 to pregreater even with the use of ear plugs as the rate vent too deep ear penetration as shown in Fig. 1. of pressure change is increased, even when low The mass may also be rubber mixed with a memaximum pressures are encountered. It, theretallic salt of the type shown in Fig. 2. In other fore, appears that damage is caused by the rate Words y relatively h h density t rial will of rise of pressure which is a shock function. sufiice.

An object of this invention is to provide an A small perforation or channel 3 is provided to ear plug capable of offering sufficient mass imextend through the mass designed to pass audible pedance to resist sudden pressure changes with quency and moderate intensity of peech and a minimum of exposed area and provided with being small enough to prevent high pressure or means for hearing conversation, and equalizing energy sounds from DaS gso doing the perair pressure in the outer ear canal. forated Plug acts to d p ds or noises of Details of the invention will become apparent hi frequency d l filter S u ds of high infrom a description of the following figures in n i y n pr ure. wh h; The filtering protection of the perforation or Fig. 1 is a cross section of a hearing guard and tube 3 is a function of e th and diameter of ear protector provided with a heavy mass imp pedgmce b If the air confined in the outer ear canal 6 in Fig. 2 is a cross section of an ear protector of front of the drum membrane pamlm heavy mass in which the mass of the protector 1 and the tubular op ning i the P commilhiperforms t e required impedance function; cating therewith is considered as a resonator with Fig. 3 shows the ear protector of Fig. 2 inserted a restricted neck as Shown in then, in the outer ear canal. Z

In Fig. 1 an ear protector l of any well known Natural frequency of the System fn= design is provided with a heavy mass impedance member 2, as shown. It will be noted that the M =inertence heavy mass inertia plug is perforated at 3 for a r purpose later described.

Without any protection the air in the external passage of the ear canal is compressed when acted on by a blast force resulting in acceleration of the ear drum. A heavy mass plug in the V C capacitance =density l=length of tube R=radius of tube outer ear offer impedance t0 V=chamberv01ume changes of pressure. The resistance offered by c=velocity of sound in air the mass to wave fronts of high intensity will Re R prevent injurious blast shock on the ear drum f,.= =K= and increase the efficiency of the ear protector. zl/Vl It has been found that a lead plug weighing in which K is a constant for all practical pur- .005 pound will accelerate approximately /iooo poses. as much as would the ear drum without pro- It i 61'flf016, ap nt th fr q n y Of he

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US302738 *Mar 13, 1884Jul 29, 1884 Ear-guard
US1016877 *Jan 18, 1911Feb 6, 1912 Ear-protector.
US2053995 *Jan 17, 1935Sep 8, 1936Leo M HoeyEar plug
US2246737 *Aug 7, 1939Jun 24, 1941Knudsen Vern OEar stopper
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2458884 *Jan 3, 1946Jan 11, 1949John VolkmannEar protector valve
US2573923 *Apr 7, 1950Nov 6, 1951David MezzEar protector
US2670738 *Mar 14, 1952Mar 2, 1954Thomas GibbonsEar protector
US2717596 *Apr 26, 1954Sep 13, 1955Knight John SCushion mounting for mass impedance resonance filter
US3831398 *Apr 4, 1972Aug 27, 1974J DavisOrnament with securing means
US4034759 *Aug 27, 1975Jul 12, 1977Xomed, Inc.Moisture-expandable prosthesis
US4326512 *Feb 14, 1980Apr 27, 1982Peerless Sidney AComposite ventilation tube for the middle ear
US4353364 *Apr 10, 1980Oct 12, 1982Woods Thomas JEar acoustical attenuating device
US4867149 *Dec 16, 1988Sep 19, 1989Cabot CorporationEarplugs
US4975967 *May 22, 1989Dec 4, 1990Rasmussen Steen BEarplug for noise protected communication between the user of the earplug and surroundings
US5467784 *Aug 16, 1994Nov 21, 1995Mobley; J. PhilPressure-regulating ear plug
US5775336 *May 31, 1996Jul 7, 1998Georgetown UniversityTubular medical device
US5819745 *Oct 24, 1997Oct 13, 1998House Ear InstitutePressure-regulating ear plug
US6568394Oct 16, 2001May 27, 2003Cabot Safety Intermediate CorporationFlanged earplug
US8297287 *Apr 24, 2003Oct 30, 20123M Innovative Properties CompanyFlanged earplug
US8733584 *Jul 31, 2006May 27, 2014Gerald Keith AuzenneBeverage container stopper systems
DE3605597A1 *Feb 21, 1986Oct 2, 1986Cabot CorpOhrstoepsel
EP0092362A2 *Apr 12, 1983Oct 26, 1983Clayton H. AllenNonlinear passive acoustic filtering
WO1997009011A1 *Sep 1, 1995Mar 13, 1997House Ear InstPressure-regulating ear plug
WO1997018779A1 *Sep 30, 1996May 29, 1997House Ear InstPressure-regulating ear plug
WO2011061451A1 *Nov 19, 2010May 26, 2011Sport ControleDevice for protecting an ear
Classifications
U.S. Classification128/867, 220/DIG.190
International ClassificationA61F11/08
Cooperative ClassificationY10S220/19, A61F11/08
European ClassificationA61F11/08