4,672,976
`[11] Patent Number:
`United States Patent 5
`
` Kroll [45] Date of Patent: Jun. 16, 1987
`
`
`[54] HEART SOUND SENSOR
`[75]
`Inventor: Mark W.Kroll, Rogers, Minn.
`{73] Assignee: Cherne Industries, Inc., Minneapolis,
`Minn.
`[21] Appl. No.: 872,514
`[22] Filed:
`Jun. 10, 1986
`[50] Bite us cise caiinactenticanianeciinniean A61B 7/02
`[52] US. C1. ceeeresseeeeconsseseecnsnnneensnnnes 128/715; 128/773;
`;
`381/169; 381/187
`[58] Field of Search..........+ 128/715, 773, 660, 639,
`128/644, 802-803; 381/153-154, 169-169,
`187-188
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`1,282,908 10/1918 Miller .......-ssesereesees 128/715 X
`“= emia
`as anon Saas
`
`
`198/715 X
`2,702,354 2/1955 Chorpening .
`ae 128/715 X
`6/1968 Young......
`3,387,149
`
`3,525,810
`8/1970 Adler......
`cessaseenses 179/1
`
`3,573,394 4/1971 Birnbaum
`- 128/715
`7/1976 Green......
`3,971,962
`128/660 X
`
`5/1979 Russell .....
`4,154,231
`es NABFE0S
`
`we TIOAL
`4,170,717 10/1979 Walshe....
`
`128/773
`4,216,766
`8/1980 Duykers..
`
`4,220,160 9/1980 Kimball.......
`.... 128/715
`4,409,986 10/1983 Apple etal. .
`vee 128/715
`
`7/1984 Dickson......
`- 128/715 X
`4,458,687
`4,483,343 11/1984 Beyer et al.
`....ssessecsssssesseees 128/660
`
`4,559,953 12/1985 Wright et ab. oo 128/715 X
`OTHER PUBLICATIONS
`
`phone”; JEEE Trans. on Sonics and Ultrasonics, vol.
`SV=29;No. Hl 982, pps 18-85,
`Primary Examiner—Lee S. Cohen
`Assistant Examiner—Angela D. Sykes
`Attorney, Agent, or Firm—Anthony G. Eggink
`[57]
`ABSTRACT
`_—A heart sound sensing device for placement on the body
`of a patient and for the detection of low frequency
`sound waves. The device is for use with medical diag-
`nostic devices, and comprises a cylindrical housing
`structure for retaining the remaining elements of the
`device, a strap for holding the device to the body of the
`patient, a fluid ingress/egress aperture, an open end for
`receiving sound _Waves, and a hydrophone assembly
`centrally fixed within the housing structure for produc-
`ing electrical signals in response to transmitted heart
`sound waves. The device of this invention is further
`provided with a flexible diaphragm whichis vibratingly
`sensitive to sound waves generated by the patient’s
`heart and being for placementin direct contact with the
`patient body surface to conform to the body contours.
`A bubblefree fluid medium is provided to fill the re-
`maining interior volume of the housing structure to
`H
`5
`transmit sound waves from the diaphragm to the hydro-
`phone assembly. The device further includes a cable
`means communicatively connected to the hydrophone
`assembly for transmitting electrical output signals to
`medical diagnostic devices. The sound sensing deviceis
`further used in a methodfor sensing heart sound waves.
`
`Bacon; “Characteristics of a PVDF Membrane Hydro-
`
`16 Claims, 6 Drawing Figures
`
`10
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`0001
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`Apple Inc.
`APL1045
`U.S. Patent No. 8,652,040
`
`Apple Inc.
`APL1045
`U.S. Patent No. 8,652,040
`
`0001
`
`

`

`U.S. Patent
`
`Jun. 16, 1987
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`U.S. Patent
`
`Jun. 16, 1987
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`1
`
`HEART SOUND SENSOR
`
`4,672,976
`
`2
`although hydrophones have been used in the acoustic
`art for specific applications, they have not been used in
`heart sound sensing devices of this nature.
`The flexible membrane or diaphragm of the sound
`sensor device easily conforms to the contours of the
`patient body surface. This structural configuration and
`cooperation of elements enhances heart sound signal
`transfer and resolution by minimizing body surface and
`device gaps. Further, the flexible device structure mini-
`mizes sound wave loss and distortion by minimizing
`acoustical parameter differences between the materials
`used in tts construction and patient body tissues.
`A hydrophonic gel material, or a bubble-free liquid
`media,
`is provided to fill the interior of the housing
`structure and which serves to accurately transmit sound
`waves from the diaphragm to the immersed hydro-
`phone assembly. Because prior art sound sensors gener-
`ally utilize water as an acoustic transmission medium,
`the suspended gas bubbles contained therein can result
`in high sound wave attenuation or energy loss. These
`losses are primarily due to viscous forces as well as heat
`conduction losses associated with the compression and
`expansion of small gas bubbles by the passing sound
`wave.
`
`Sound wavescattering is a further detrimental effect
`caused by gas bubbles in a transmission medium, and
`whichresults in the loss of energy in the sound wave.
`The presence of gas bubbles also affects the nature of
`the medium through which the wave progresses by
`altering its density and compressibility to,
`thereby,
`change the sound wave speed. Such medium alterations
`can result in a considerable amount of acoustic energy
`reflection and refraction losses. The device ofthe pres-
`ent invention is constructed to overcome the problems
`associated with the use of a water medium in sound
`sensor designs as well as the other prior art limitations
`previously described.
`These and other benefits of this invention will be-
`comeclear from the following description, by reference
`to the drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 showsa pair of heart sound sensor devices of
`the present invention placed in an operative position on
`the chest area ofa patient;
`FIG. 2 is a view in perspective of the present inven-
`tion and showing the device partially in cross-section
`for clarity;
`FIG.3 is a cross-sectional view taken along lines 3—3
`of FIG. 2 and which showsthe interior of the sound
`sensor device housing structure;
`FIG. 4 is a cross-sectional side view taken alonglines
`4—4 of FIG. 5 showing another embodiment of the
`hydrophone assembly utilized in the sound sensor of the
`present invention;
`FIG. 5 is a schematic view of the sound sensor device
`with cut-away portions to further show the hydrophone
`assembly of FIG. 4; and
`FIG. 6 is a cross-sectional side view taken along lines
`6—6 of FIG. 5 and which showsthe transducerof the
`hydrophoneassembly.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`FIG. 1 showsa pair of sound sensing devices 10 in an
`operative position at predetermined locations on the
`precordial region 60 of a patient. In use, prior to such
`
`BACKGROUNDOF THE INVENTION
`
`This invention relates to medical diagnostic devices
`and, more particularly, to medical sensing devices used
`to detect energy in the audible range. This invention is
`particularly useful for the detection of a broad range of
`frequencies of bioacoustic waves generated by the
`humanheart.
`In the past, a variety of devices have been utilized to
`detect heart sounds. These devices range from primar-
`ily mechanical devices, such as the stethoscope, to vari-
`ous electronic devices, such as microphonesand trans-
`ducers. These prior art devices have various limitations
`including the inability to simultaneously detect high and
`low frequencies, the requirement of continuous “hand-
`s-on” operator manipulation, and sound wavedistortion
`and attenuation.
`Despite the need for a bio-acoustic sensing device in
`the medical diagnostic art which provides for the reli-
`able transmission of sound waves, particularly in the
`sub-kilohertz (KHz) range, and which overcomesthese
`prior art limitations, none insofar as is known has been
`proposed or developed.
`Accordingly, it is an object of the present invention
`to provide a device that is easy to operate, that detects
`a broad range of heart sound frequencies, particularly
`low frequency sounds, and that minimizes heart sound
`wave distortion and attenuation.
`
`SUMMARYOF THE INVENTION
`
`The heart sound sensing device is for placement on
`the body ofa patient to detect bio-acoustic signals. The
`device is for use with medical diagnostic devices, and
`comprises a cylindrical housing structure for retaining
`the remaining elements of the device, a securementbelt
`assembly for holding the device to the body of the
`patient, a fluid ingress/egress aperture, an open end for
`receiving sound waves, and a hydrophone assembly
`centrally fixed within the housing structure for produc-
`ing electrical signals in response to transmitted heart
`sound waves.
`The housing structure is further provided with a
`flexible diaphragm disposed across its open end for
`placement in direct contact with the patient body sur-
`face and an interior having a bubble free fluid medium
`which permits sound wave transmission from the dia-
`phragm to the hydrophoneassembly.
`The device of this invention further includes a cable
`means communicatively connected to the hydrophone
`assembly within the housing structure for transmitting
`electrical signals to medical diagnostic devices.
`The device is generally thin and flat so that it will
`easily remain in a predetermined location on the precor-
`dial region of a patient. The securement belt assembly
`provided further enables one or a plurality of devices to
`be affixed in an operative position on the axillary region
`of the patient or to any body surface whenthepatient is
`either in a horizontal or non-horizontal position. Many
`prior art devices require continuous operator manipula-
`tion when in use because of their design features.
`The device has a configuration which includes a
`hydrophone assembly which easily permits the detec-
`tion of low frequency soundsignals, particularly in the
`sub-KHz range, because of its sound wave reception
`aperture size. Prior art devices have been limited in
`their capacity to detect low sound frequencies, and,
`
`5
`
`30
`
`40
`
`45
`
`60
`
`65
`
`0004
`
`0004
`
`

`

`4,672,976
`
`0
`
`5
`
`20
`
`40
`
`45
`
`3
`placement. an acoustic coupling compound, such as
`Aquasonic 100 (T.M.), produced by Parker Labs. or
`Lectro-Sonic (T.M.), produced by Burdick, is applied
`to those predetermined locatins. A physician or other
`medical personnel determines the appropriate position-
`ing locations on the precordial region for each device
`10 depending upon the patient and upon the nature of
`the diagnostic test to be performed. The devices 10 are
`shown held in place by a strap means 11 which loops
`through securement means 34 of devices 10. The strap
`11 is generallya flexible strap or band having end con-
`nectors or like fastening means to adjustably secure the
`devices 10 to the bodyof the patient.
`The sound sensing device 10 is used to receive bio-
`acoustic signals from the body ofa patient. As shown in
`FIG. 1, the sound sensing devices 10 are arranged to
`receive transmitted sound waves from the heart of a
`patient and to convert the sound waves intoelectrical
`signals for use. The device 10, or a plurality of such
`devices 10 as shown, are used in conjunction with a
`medical diagnostic device 13 which processes electrical
`signals. The device 10 is communicatively connectable
`to the medical diagnostic device 13 via a cable or cable
`set 12. Subsequent to connection of the device or de-
`vices 10 to the medical diagnostic device 13, a sound 2
`sensing and analysis procedure is conducted. Addition-
`ally, as is shown in FIG. 1, the device 13 may be com-
`municatively linked to a printer 14 for printed copy of
`diagnostic results.
`FIGS. 2 and 3 show the sound sensing device 10
`being comprised of a housing structure 15, a hydro-
`phone assembly 26, a diaphragm 21, a hydrophonic gel
`medium 25 and a cable 12. The housing structure 15 is
`preferably cylindrical with one closed end and having a
`rigid portion 16, a pliant or semi-rigid portion 17, se-
`curement means 34,a fluid ingress/egress aperture 18,
`and a sound wave reception aperture 20. The housing
`structure 15 retains the operative elements of device 10
`and also provides a chamber to receive transmitted
`sound waves. Securement means 34 of housing struc-
`ture 15 serves to adjustably hold the strap or secure-
`ment belt 11 to the device 10. The securement belt 11 is
`also able to adjustably hold a second sound sensing
`device 10, as shown in FIG. 1, andit also is provided
`with fastening means, such as a buckle or Velcro-fasten-
`ing system to permit the adjustable securement of de-
`vices 10 about the chest of a patient.
`The open bottom end or sound wave reception aper-
`ture 20 of housing structure 15 allows ingress of the
`transmitted sound waves. The sound wave reception
`aperture 20 is preferably 5 cm in diameter in one em-
`bodimentof the invention to allow for ingress of wave-
`lengths on the order of magnitude of 10 cm. In this
`embodiment,
`the sound wave reception aperture 20
`consists of the entire open end ofthe cylindrical housing
`structure 15 for the detection of low frequency sound
`waves.
`
`The housing structure 15 shown has two-part body
`design; however, other housing structure configura-
`tions are also within the purview ofthis invention. The
`pliant or semi-rigid portion 17 of the housing structure
`15 is flexible and comprised of a deformable and elasto-
`meric material, for example, It, therefore, conforms to
`the contours of the body surface of the individual pa-
`tient 60 to provide for a morereliable and less distorted
`sound wave reception because ofits conforming place-
`ment and because its acoustical parameters are more
`similar to that of a patient's body. As shown, the rigid
`
`65
`
`0005
`
`+
`portion 16 provides a solid support structure for the
`remaining elements of the device 10.
`The diaphragm 21 ts preferably flexible and thin, and
`sealingly covers the sound wave reception aperture 20
`of housing structure 15. The diaphragm 21, as shownin
`FIGS. 2 and 3, has a retainer ring 22 which is a thick-
`ened peripheral portion in the diaphragm material itself
`or which can be a separate mechanical member. The
`diaphragm 21 is fixed to the housing structure 15 by the
`cooperation of the retainer ring 22 with the annular
`groove 23 in the pliant portion 17 of the housing struc-
`ture 15. Alternatively, the diaphragm 21 can be adhe-
`sively secured to the housing structure or the dia-
`phragm can be a thinned area and unitary with the
`pliant portion 17. It is additionally within the purview
`of the invention to provide a housing structure 15 com-
`prised of a unitary structure wherein the thickness of
`the elastomeric material is altered in the housing struc-
`ture configuration to provide a rigid top area, a semi-
`rigid lateral area and a flexible bottom membranearea.
`In use, the diaphragm 21 is placed in direct contact
`with the patient body surface 60 (See FIG. 1) to which
`has been applied the acoustic coupling compound. The
`flexible diaphragm 21 conforms to the contour of the
`body surface to vibratingly receive sound waves trans-
`mitted from the patient's heart. The vibrations of the
`diaphragm 21 are transmitted to the hydrophone assem-
`bly 26 through the hydrophonic gel 25, which com-
`pletely fills the inner cavity 24 of the housing structure
`15. The hydrophonic gel 25 is a bubble-free, liquid,
`sound-transmission media such as Aquasonic 100 (T.M.)
`or Lectro-sonic (T.M.), compounds previously dis-
`cussed. The air bubble-free media provides for an effi-
`cient transmission of acoustic waves so as to minimize
`acoustic energy losses due to gaseous interference. The
`fluid ingress-egress aperture 18 in housing structure 15
`allows for filling and removal of the hydrophonic gel
`25, The aperture 18 is sealable by a screw or plug 19.
`Referring to FIG. 3, the hydrophone 26 is centrally
`placed within the inner cavity 24 of housing structure
`15.It produceselectrical signals in response to transmit-
`ted heart sound waves in the frequency range of 10 to
`2,000 Hz. The hydrophone 26 is comprised of a trans-
`ducer or cantilever crystal beam 27, a current distribu-
`tion system 30, a hydrophone cavity 61 and an exterior
`insulating layer 33. The crystal beam 27is an elongated,
`thin, and flexible cantilever beam crystal preferably
`having a length of 3 cm. for receiving acoustic waves
`through a 10 cm. reception area 20. Contacts 28 are
`disposed at opposing sides of the crystal beam 27 near
`its supporting base or mounting end 29. The beam crys-
`tal 27 is located within the hydrophone cavity 61 to
`permit
`its vibration due to the impact of bioacoustic
`waves. The beam crystal 27 converts the non-electrical
`input heart sound waves for example,into an electrical
`output signal for transmission through cable set 12 via
`the current distribution system 30.
`The crystal 27 is vibratingly sensitive to sound pres-
`sure variations and a proportional electric current is
`produced byits vibration. The current distribution sys-
`tem 30 initiates in and is shielded by hydrophoneinsula-
`tion 33. The current distribution system 30 extends from
`the contacts 28 of hydrophone 26 and is additionally
`shielded by an inner insulator 31 and an outerinsulator
`32 to form a cable 12 which transfers the electrical
`output current to a heart sound analyzer apparatus 14 or
`a similar medical diagnostic device, as shown in FIG. 1.
`
`0005
`
`

`

`4,672,976
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`0
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`25
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`6
`5
`
`FIGS. 4 and 5 showaalternative hydrophone em- The crystal members 48 and 49 are of the type which
`bodiment 35. Hydrophone 35, as manufactured by Mark
`exhibit
`the piezoelectric effect. Transmitted sound
`Products, Inc. of Houston, Tex., is shown to be com-
`waves subject the crystal members 48 and 49 to a me-
`prised ofa circular plate transducer 36, transducerinsu-
`chanical stress which sets up an electrical polarization
`lation 42, a transformer 40, transformer insulation 43,
`in each crystal and which cause the faces of each crystal
`low voltage lead wires 38, lead wires 30 and an exterior
`to become electrically charged. The polarity of the
`hydrophoneinsulation layer 44. The transducer 36 con-
`charges reverses as crystal compression changes to
`verts input non-electrical bio-acoustic or heart sound
`crystal tension. There is an approximatelylinear rela-
`waves into output electrical signal parameters. Varia-
`tionship between crystal deformation andelectric field
`tions in the frequency of the output electrical signal
`strength, The change in electric field strength along
`parameter being a function of the input parameter. The
`defined axes in the crystals can be defined by known
`transducer 36 is further enclosed by a transducer insula-
`equations relating to the incremental stress and the pi-
`ezoelectric strain constant.
`tor 42, which is composed of a non-conductive sub-
`stance that does not conduct current or voltage but does
`The electrical signal produced by crystal members 48
`conduct sound waves.
`and 49 in response to transmitted sound waves is distrib-
`Transducer 36 is communicatively connected to a
`uted to the remaining hydrophone 35 conductive ele-
`transformer 40 by a pair of low voltage lead wires 38
`ments via outer crystal lead wires 51 and an inner crys-
`tal lead wires 53. Each wire 51 and 53 is connected to
`(approximately 30 gauge). The low voltage lead wires
`38 having insulation layer 39 are attached to transducer
`the transducer contacts 37, to which the low voltage
`36 at
`transducer contacts 37. Both low voltage lead
`lead wires 38 are also attached. Outer crystal lead wires
`wires 38 with insulator layers 39 are shown embedded
`51 are substantially sheathed in insulation 52. Inner
`in transducer insulation 42. The transformer 40 is for
`crystal lead wires 53 are disposed in the transducer void
`converting the output electrical signal of the transducer
`area 54.
`36 into an electrical signal of the same frequency and
`Although two embodiments of a hydrophone assem-
`increased alternating voltage. The transformer40 is of a
`bly are here shown and described other such assemblies
`design commonly knownin the art. It has a primary and
`may also be utilized in the bio-acoustic sound devices of
`a secondary coil with a magnetic core suitably arranged
`this invention. The criteria being that the hydrophone
`between them. The output of transducer 36 is received
`assembly be mountable in a fluid medium within a hous-
`by the primary coil and, by electromagnetic induction,
`ing structure and be designed for receiving and trans-
`the secondarycoil delivers an electrical outputsignal of
`mitting the bio-acoustic waves and corresponding elec-
`an increased voltage. The transformer 40 is enclosed by
`trical outputsignals as discussed above. Once assembled
`a transformerinsulator 43 whichis of a non-conductive
`as shown and described, the bio-acoustic sensor of this
`material.
`inventionis utilized in various medical diagnostic pro-
`As shown, the current distribution system or lead
`cedures. Particularly of importance in this invention, as
`wires 30 are connected to transformer 40 at contacts 41,
`discussed, is the structural arrangementof a heart sound
`and they conduct the transformed electricalsignal to a
`sensor utilizing a hydrophone assembly which cooper-
`heart sound analyzing apparatus 13. Lead wires 30 have
`ates with the other elementsof the sensor to detect heart
`a non-conductive inner insulator 31 and a non-conduc-
`sounds in the sub-KHz range.
`tive outer insulator 32 which collectively form cable set
`12.
`In use, the practitioner or researcher selects an area
`on the thoracic region of the body of a patient for heart
`The hydrophone 35 elements described above and
`sound wave reception and utilizes a medical diagnostic
`shown in FIG. 4 are further enclosed by an exterior
`device to analyze heart sound waves. The heart sound
`insulation layer 44. The hydrophoneinsulation 44 pro-
`sensing device is placed and arranged whereby the
`tects and electrically insulates the hydrophone elements
`diaphragm is in contact with the body surface area of
`40 in the liquid environment of the hydrophonic gel 25.
`the patient, and the cable means is connected to the
`The hydrophoneinsulation layer 44 is composed of a
`medical diagnostic device to accomplish a diagnostic
`substance which does not conductelectricity, but does
`heart sound analysis procedure.
`conduct sound waves. As shownparticularly in FIG.4,
`acoustic channels 45 are formed in the insulation 44.
`As many changes are possible to the embodiments of
`this invention utilizing the teachings thereof, the de-
`The channels 45 are constructed and arranged in a gen-
`scriptions above, and the accompanying drawings
`erally concentric circular configuration on the top and
`should be interpreted in the illustrative and not
`the
`bottom faces of the hydrophone35in the areas adjacent
`limited sense.
`to the transducer 36. The channels 45 serve to provide
`That which is claimed is:
`optimal capture of transmitted sound waves. The sound
`wavesare further conducted to the transducer insulator
`1. A bio-acoustic signal sensing device for placement
`42 and then to the transducer 36.
`on the body ofa patient to detect low frequency bio-
`acoustical signals and being for use with medical diag-
`FIG. 6 showsthe circular plate transducer 36 com-
`nostic devices, comprising:
`prisingafirst plate 46, a second plate 47 and a side wall
`a. a housing structure retaining the remaining ele-
`50. The first plate 46 and a second plate 47 lie on top of
`ments of the device and having securement means
`and below the side wall 50 respectively and are bonded
`for holding the device to the body ofthe patient,
`thereto. The spacially removed plates 46 and 47 form
`said housing structure having an open end for
`the transducer void area 54. Thefirst plate 46 and sec-
`sound wave reception and a fluid ingress/egress
`ond plate 47 each serve as a base for an outer crystal
`aperture said open end having a horizontal dimen-
`member 48 and an inner crystal member 49 which are
`sion ofat least 5 cm.;
`likewise spacially separated in transducer void area 54.
`b. hydrophone means spacially fixed within said
`Thefirst plate 46, second plate 47 and side wall 50 are
`composed of a metallic substance suitable for mounting
`housing structure for producing electrical signals
`crystals.
`in response to transmitted bio-acoustic signals;
`
`30
`
`45
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`50
`
`60
`
`65
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`0006
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`4,672,976
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`
`7
`flexible diaphragm means extended across said
`open end of said housing structure and having
`retention means to fix it
`thereacross, said dia-
`phragm means being for placement
`in direct
`contact with the patient body surface, for conform-
`ing to the contours of the patient body surface and
`being vibratingly sensitive to the sound waves gen-
`erated in the patient's body;
`d. a bubblefree fluid gel mediumfilling the remaining
`interior volumeof said housingstructure, said fluid
`medium transmitting sound waves from said dia-
`phragm means to said hydrophone means; and
`e. cable means communicatively connected to said
`hydrophone means for transmitting electrical sig-
`nals from said hydrophone means to medical diag-
`nostic devices.
`2. The bio-acoustic signal sensing device ofclaim 1,
`wherein said housingstructureis further comprised of a
`rigid top portion and a pliant bottom portion,said rigid
`top portion having said fluid ingress/egress aperture
`and having said securement means,said pliant bottom
`portion defining the open end ofsaid housing structure
`and having said retention meansto fix said diaphragm
`means at its circumferential periphery, said pliant por-
`tion being for conforming to the body curvature of a
`patient
`to improve sound wave transmission to said
`housing structure.
`3. A heart sound sensing device for placement on the
`body of a patient and being for the detection of sub-
`KHz, low frequency sound waves for use with medical
`diagnostic devices, comprising:
`a. a cylindrical housing structure retaining the re-
`maining elements of the device, said housing struc-
`ture having a rigid top portion and a pliant bottom
`portion, said top portion having securement means
`for holding the device to the body of the patient
`and a fluid ingress/egress aperture, and said bottom
`portion having an open end of a diameterofatleast
`5 cm. for receiving sound waves;
`b. hydrophone means centrally fixed within said
`housing structure for producing electrical signals
`in response to transmitted sub-KHz frequency
`heart sound waves, said hydrophone means having
`a transducerand an exteriorinsulating covering for
`converting heart sound waves into electrical out-
`put signals;
`flexible diaphragm means extending across said
`open end ofsaid pliant bottom portion and having
`retention means tofix said diaphragm means at the
`periphery thereof, said diaphragm means being for
`placement in direct contact with the patient body
`surface, said diaphragm means and said pliant bot-
`tom portion conforming to the contours of the
`patient body surface and being vibratingly sensitive
`to sound waves generated by the patient’s heart;
`d. a bubble free fluid medium completelyfilling the
`remaining interior volumeof said housing structure
`about said hydrophone means and surrounding said
`hydrophone means,said fluid medium transmitting
`sound waves from said diaphragm means to said
`hydrophone means; and
`e. cable means communicatively connected to said
`hydrophone means for transmitting electrical sig-
`nals from said hydrophone means to medical diag-
`nostic devices.
`4. The sound sensing device of claim 3, wherein said
`hydrophone meansadditionally has transformer means
`for transforming the electrical output signals of said
`
`c.
`
`8
`transducer into electrical signals of the same frequency
`at increased alternating voltages, a transformer insula-
`tor, current distribution means for electrical communi-
`cation between said transducer and said transformer
`means and thin, resilient
`insulation covering for said
`transducer.
`5. The sound sensing device of claim 4, wherein said
`transformer insulatoris a rigid non-conductive material
`to provide strain relief for connection of the sensing
`device to said cable means.
`6. The sound sensing device of claim 3, wherein said
`transducer is a crystal transducer having two spaced
`quartz crystal plates producing a piezoelectric effect
`whereby sound pressure variations cause displacements
`of the crystals to produce a corresponding voltage.
`7. The sound sensing device of claim 6, wherein said
`hydrophoneexterior insulating covering has a plurality
`of annular channels normal said quartz crystal plated to
`improve sound wave reception thereto.
`8. The sound sensing device of claim 3, wherein said
`transducer is a cantilever beam crystal transducer hav-
`ing an elongated, thin and flexible crystal at least 3 cm.
`in length, a base structure to support the cantilevered
`beam, and twoelectrical contact points being on oppo-
`site sides of said crystal adjacent the base structure for
`communicating with said cable means of the heart
`sound sensing device, whereby sound pressure varia-
`tions cause said flexible crystal to vibrate and produce a
`corresponding voltage.
`9. The sound sensing device of claim 3, wherein said
`transducer exterior insulating covering is an elastomeric
`substance which permits the conduction of sound
`waves.
`
`10. The sound sensing device of claim 3, wherein said
`diaphragm retention means is comprised of an exteri-
`orly disposed annular groove in said housing structure
`adjacent its open end and a retention ring to securing
`said diaphragm meansin a taut configuration across said
`open end.
`11. The sound sensing device of claim 10, wherein
`said diaphragm means is comprised ofa circularelasto-
`meric material and wherein said retention ring is com-
`prised of a thickened outer circumferential portion for
`seating in said housing structure annular groove.
`12. The sound sensing device of claim 3, wherein said
`fluid medium is a phono-transmitting gel.
`13. The sound sensing device ofclaim 3, wherein said
`housing structure securement meansis comprisedofat
`least one exteriorly disposed slotted memberand a strap
`means having connector ends for placement
`there-
`through to adjustably secure said sound sensing device
`on the body ofa patient.
`14. A method of sensing heart sound waves compris-
`ing:
`a. selecting an area on the thoracic region of the body
`ofa patient for heart sound wave reception;
`b. providing a medical diagnostic device to analyze
`heart sound waves;
`c. providing a heart sound sensing device having:
`(1) a housing structure retaining the remaining
`elements of said heart sound sensing device and
`having securement means for holding said device
`to the body of the patient, said housing structure
`having an open end for sound wave reception
`and a fluid ingress/egress port, said open end
`having a horizontal dimension ofat least 5 cm.;
`
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`4,672,976
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`9
`(2) hydrophone means placed within said housing
`structure for producing electrical signals in re-
`sponse to transmitted heart sound waves;
`(3) flexible diaphragm means for placement in di-
`rect contact with the patient body surface and
`which conforms to the contours of the patient
`body surface and whichis vibratingly sensitive
`to the sound waves generated by the patient's
`heart, said diaphragm means being extended
`across said open end of said housing structure
`and having retention means to fix it thereto;
`(4) a bubble free fluid medium transmitting sound
`wavesfrom said diaphragm meansto said hydro-
`phone means, said fluid medium filling the re-
`maining interior volume of said housing struc-
`ture; and
`(5) cable means communicatively connectedto said
`hydrophone meansfor transmission of electrical
`
`10
`signals from said hydrophone means to said med-
`ica] diagnostic device;
`d. placing and arranging said heart sound sensing
`device whereby said diaphragm meansis in contact
`with said body surface area of the patient;
`e. connecting said cable means to the medical diag-
`nostic device; and
`f. performing a diagnostic heart sound analysis proce-
`dure.
`15. The method of claim 14, wherein an acoustic
`coupling compoundis appliedto the selected area ofthe
`body of the patient.
`16. The method of claim 14, wherein a pair ofsaid
`sound sensing devices are provided and positioned on
`the thoracic region ofthe patient, one said device being
`placed on the precordial region of the patient adjacent
`to the sternum and said other device being placed on the
`high axillary region.*
`*
`*
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