Abstract: A method for fabricating an object to attenuate thermal sensation when handling the object at non-body temperature, and an object fabricated in accord with the method. There is first provided a substrate which has a first surface subject to handling. There is then formed upon the first surface of the substrate a coating. The coating has an optimal density, an optimal thermal conductivity and an optimal thickness such that when the substrate having the coating formed thereupon is equilibrated at a non-body temperature differing from a body temperature and the coating is subsequently contacted with a body at the body temperature during handling, the temperature of the surface of the coating at a contact point of the body with the coating changes precipitously to a temperature near the body temperature and subsequently returns towards the non-body temperature at a rate which permits handling of the coating at the location of the first surface of the substrate by the body with attenuated thermal sensation.

Abstract: A self-contained, hand-held electronic stethoscope including built-in chestpiece, speaker and visual monitor, includes a memory containing prerecorded heart and lung sounds along with a brief description of the malady producing the sounds so that the technician may compare the actual sounds with the prerecorded sounds and observe a suggested diagnosis on the monitor.

Abstract: The diaphragm assembly includes a diaphragm adhesively attached to a rim. The rim has a C-shaped cross section with the C-shape facing inward and a membrane extending radially inward from one of the radial portions of the C-shaped portion. The diaphragm is attached to the membrane. The thickness of the membrane is about two tenths of the thickness of the section of the C-shaped portion. The groove formed by the C-shape engages a rib on a stethoscope chest piece to install the diaphragm assembly.

Abstract: The practical stethoscope cover of this invention in its most essential elements, comprises any form of material which acts as an effective, inexpensive and acoustically transmissive barrier means for easy application and removal from the head, or heads, of a stethoscope. The barrier means should be non-transmissive for dirt, organisms, oils, fluids and the like, all of which may carry pathogenic components. Significantly, embodiments of the stethoscope cover of this invention are easily applied by a physician, nurse or other medical practitioner to the head of a single-headed stethoscope or a double-headed stethoscope, typically in a quick, simple, easy single-handed operation. The barrier means comprising the stethoscope cover comprises folds, gathers or crimping at the marginal edges or medial portions thereof, providing flexibility, extensibility or elasticity to the cover, thus facilitating easy application and removal of the stethoscope cover from the head of the stethoscope.

Abstract: A stethoscope is described. The stethoscope includes a head assembly, an ear piece assembly, and a tubing assembly. The tubing assembly has a first end connected to the head assembly and a second end connected to the ear piece assembly. The tubing assembly includes a first acoustic chamber and three insulation chambers. The insulation chambers include a first material having a first density and are disposed around the first acoustic chamber. The tubing assembly also includes an outer layer, which includes a second material having a second density. Moreover, the outer layer is disposed around the insulation chambers. In another embodiment, the outer layer is substantially frictionless and the tubing assembly is flexible. In yet another embodiment, the stethoscope further includes a second acoustic chamber and the insulation chambers are disposed around a portion of the first acoustic chamber and a portion of the second acoustic chamber.

Abstract: A stethoscope including a dual head chest piece with removable diaphragm structures and bell components for adapting the stethoscope for use with infants or adults, or on sites having less skin area, such as the ribs. The stethoscope further includes a single tube for connecting the chest piece to the ear piece. Because the stethoscope uses only a single tube sound passage system, the stethoscope is smaller and lighter in weight, and thus, less cumbersome and less costly to make than the traditional convertible dual head stethoscope.

Abstract: A electronic stethoscope head is combined with a standard stethoscope air tube headset assembly to provide a personally portable ECG stethoscope system for auscultating a living body. The electronic stethoscope head comprises a stethoscope body having a chest-bell, an air tube connector (or connectors), and a display module mounted to it. The chest-bell has a rim for contacting the body, and a base adapted to attach to the stethoscope body. An electrode assembly having at least two electrodes is disposed on the rim of the chest-bell to contact the body during auscultation and receive electrical signals from the body. The electrical signals are conducted to the display module. The display module is mounted on the stethoscope body, and receives and processes the electrical signals and display a representation of the electrical signals on a view screen, like an LCD display screen.

Abstract: The tube assembly is made up of an outer, elastomeric tube, a close wound metal spring inside the outer tube and a layer of material inside the spring to provide a smooth inner surface for the assembly. The layer may be a thin-walled elastomeric plastic tube or a layer of elastomeric material applied to the inside of the spring. Also, the spring wire may be coated with elastomeric plastic.

Abstract: A stethoscope head for joining to an earpiece assembly. The head has a generally tubular neck for joining the head to the earpiece assembly. An anterior chamber has an open face with an aperture at its apex and an outer rim. The bell is adapted to gather and reflect sound originating at or near the open face toward the aperture. A thin disposable diaphragm has adhesive on one side for releasably adhering to the rim. A central chamber is adjacent the bell and connected to the bell by the aperture. The chamber is adapted to direct sounds from the aperture to the neck.

Abstract: A stethoscope head for a one-way stethoscope with a membrane. The stethoscope has a funnel or bell-shaped resonance body. A membrane and the resonance body enclose a resonance chamber that is interconnected to the air column in the lumen of a tube. A capsule of a soundproof material completely surrounds a distal region of the resonance body without contact, leaving just an opening through which the tube passes. A suspension element of elastomer material forms a mobile connection between the capsule and the holding ring attached to the peripheral rim of the resonance body.

Abstract: A device for use in a stethoscope, the device including two diaphragm-type sound accumulator chambers, one microphone located in each accumulator chamber and one amplification stage connected to each microphone for electronically amplifying audio signals received by the microphones, and an output connector for outputting the amplified audio signals.

Abstract: A stethoscope having a chest-piece which is composed of a base member fixed to flexible tubes, a pickup mounting member rotatable about a first axis relative to the base member, and a plurality of pickups carried by the pickup mounting member. The plurality of pickups consist of one diaphragm and one bell; the diaphragm and the bell extend in diametrically opposite directions perpendicular to the first axis and extend along a common axis of symmetry; the bell has an outer end which lies in a first plane remote from the first axis, an inner end between the outer end and the first axis and a curved wall between the outer and inner ends; and the outer end has an external diameter less than 30 mm.

Abstract: A cover for a stethoscope head having a discontinuous layer of peelable adhesive in a predetermined pattern for detachable affixing to the head of the stethoscope including the diaphragm and the preselected pattern has a plurality of spaced apart adhesive segments and provides air flow passages from regions between the cover and the diaphragm to regions external the stethoscope to prevent the formation of air pockets and bubbles therebetween.

Abstract: A stethoscope having a light source includes a stethoscope head and flexible tubing coupled to the stethoscope head and in communication with ear pieces for the detection and transmission of sounds from a patient's body. A casing is affixed to a cover of the stethoscope head and has a light source mounted therein. A switch is operable mounted on the casing for activating and deactivating the light source. Notches extend intermediate the casing and cover for grasping the same during use. A first end of the casing is disposed toward a perimeter of the cover and has an aperture through which light is emitted. The first end is adapted for mounting thereon various instrument heads as an otoscope or opthalomoscope. The first end may extend beyond the perimeter of the cover for mounting thereon the instrument heads. In an alternative embodiment, the casing is detachably secured to the flexible tubing of the stethoscope.

Abstract: Acoustic point source transducer apparatus including a high-output acoustic sound source propagating sound through a long, flexible tubing having an open end with a small diameter. Sound radiates from the small diameter open end effectively acting as an acoustic point source. A flexible sleeve encasing the terminal end of the tubing permits convenient wand-like placement of the acoustic point source by a human operator and an electromagnetic position sensor at the small diameter open end determines point source position. The invention provides a convenient, nondirectional approximated acoustic point source for improved acoustic measuring, especially desirable for near-field Head-Related Transfer Function measuring.

Abstract: A noise blocking band earplug has a band (12) with outer portions (44, 46) that are bent to prevent the ear-engaging pods (20, 22) from touching the ground, whether placed right-side-up or upside-down on the ground. When the middle region (32) of the band rests on a horizontal surface (64), a band inner end part (70) extends at an upward incline (C) with its outer end forming a second bend (80) so the outer end part (72) extends at a downward incline (D), with the second bend preventing the pods from touching the ground when the earplug is laid upside-down. At the second bend (80), the largely vertical height (J) of the band is increased and its outer surface (102) is made convex to provide pads for more readily pressing the pods against the outside of the ear canals.

Abstract: An acoustic device has first and second conduits such that the first conduit has an inlet and an outlet, and the second conduit encloses a material that is different from the material in the first conduit, or encloses the same material as that in the first conduit but at a different pressure. The first and second conduits share a common wall that is made up of a flexible membrane that allows acoustic signals in the first and second conduits to be acoustically coupled together, thereby allowing acoustic signals in the first conduit to be altered to suppress, enhance, or change certain aspects of the acoustic signal without the use of electronics.

Abstract: A stethoscope supporting device is provided including a back plate and front portion for securing a stethoscope to the back plate. Connected to the back plate is a clip for securing the same on an article of clothing.

Abstract: A plurality of single diaphragm cover dispensable assemblies (11) each of which has a stethoscope diaphragm cover (12) having a thin plastic body member (16) to which there is applied a pressure sensitive adhesive layer (26) mounted on an adhesive protective layer (14) on a first surface (30). A stacking pressure sensitive adhesive layer (34) is on the adhesive protective layer (14) in a location spaced from the portion (28B) attached to the cover (12). The stacking pressure sensitive adhesive layer 34 may be on the first surface (30) or the second surface (32) of the adhesive protective layer (14). A plurality of the assemblies (11) are in a stacked aligned array with the stacking pressure sensitive adhesive layers (34) providing the detachable coupling of one assembly (11) to the next assembly (11) in the stack.

Abstract: A stethoscope, and a stethoscope chestpiece, with an increased signal to noise ratio. The invention concerns mechanical improvements to both traditional mechano-acoustic stethoscopes, and to electronic stethoscopes. The stethoscope chestpieces of this invention are constructed so that the transducers are responsive to the pressure differences between air pressure variations in the chestpiece air cavity which is coupled to the skin, and the air pressure variation due to ambient noise present in the environment. The result is a transducer output with increased signal to noise ratio.

Abstract: An electronic stethoscope emulates the frequency response of a standard acoustical stethoscope in both bell and diaphragm modes, while providing additional features attainable only with an electronic stethoscope, such as signal amplification, noise reduction, wider bandwidth, and mode selection. The electronic stethoscope includes spectrally separate idealized diaphragm and idealized bell modes. The idealized diaphragm mode and the idealized bell mode each include emphasized passbands and de-emphasized passbands. The emphasized passbands are spectrally separate. In addition, the electronic stethoscope also includes a wideband mode, which permits the user to hear high frequency sounds such as those associated with mechanical heart valves, lung sounds, and the like.

Abstract: A cover diaphragm is removably attached over the outer edge of a stethoscope high frequency pickup in order to isolate the pickup from pathogens contacted when the stethoscope is used to examine a person. The cover diaphragm can be used as the diaphragm of a stethoscope high frequency pickup and can be used with a diaphragm supplied with the stethoscope. After the cover diaphragm has been used it can be discarded and destroyed by known safe procedures and alternatively can be cleaned by known safe procedures for reuse.

Abstract: A thin, disposable shield serves as a sanitary cover as well as a diaphragm for a stethoscope. The shield has a circular line of perforations, resulting in a central disk portion and an outer ring portion. The shield is releasably secured to the rim, preferably by adhesive, to protect a patient from contact with the rim. The shield itself serves as the diaphragm, vibrating with sound transmission. The perforations optionally allow the disk portion to be punched out to provide an unobstructed path for sound transmission of lower frequency. If the forward face of the threaded ring of a conventional stethoscope is not flat, a substitute ring may be secured in place of the conventional ring. The substitute ring has a flat face that is perpendicular to the longitudinal axis. The flat face enhances the ability of the shield to stick to the ring.

Abstract: A stethoscope head with multiple removable diaphragm structures and bell components for adapting the stethoscope for use with infants or adults, or on sites having less skin area, such as between the ribs is described. The bell components further include a wider rim than a conventional rim for better acoustically sealing the rim to the skin of the patient's body above the site to be auscultated. Further, the bell component is metallic providing for better sound conductivity than a non-metallic bell component. A non-metallic ring is disposed on the rim to better acoustically seal the rim with the skin of the patient's body and further, provide comfort to the patient since the non-metallic ring is not as cold as the metallic rim. The bell component includes a thick body to exclude external noises from interfering with the sound to be auscultated.

Abstract: A stethoscope shield unit comprising a plurality of substantially planar shield stacked one upon the other, each of the shields including a first surface having an adhesive applied thereto and a second surface such that adjacent shields adhere to one another with the first surface of each of these shields adhering to the second surface of an adjacent shield with a first shield of the plurality of shields being adhered to the diaphragm of the stethoscope for supporting the plurality of shields wherein an exposed shield of the plurality of shields is removed after contacting the body of a patient. A protective shield devoid of an adhesive may be positioned adjacent the first shield of the plurality of shields with the protective shield being removed prior to adhering the first shield of the stack to the diaphragm.

Abstract: An elastic sheath and a retaining ring is provided for a stethoscope having a head, a sound tube and an earpiece. The sheath has an open end for admittance of the head and a portion of the sound tube and a closed end. The sheath is sized such that the head of the stethoscope and at least a portion of the sound tube is enveloped by the sheath. The retaining ring is mounted to the sound tube and extends radially outwardly therefrom. The retaining ring is sized such that the sheath plastically deforms to envelop the retaining ring. The retaining ring thus releasably retains the sheath on the stethoscope.

Abstract: An electronic stethoscope having several modes of operation to process acoustic signals to provide filtered signals useful for diagnosis. In one mode of operation the stethoscope substantially provides only acoustic signals generated by biological activity of the heart. In another mode of operation, the acoustic stethoscope substantially provides only acoustic signals generated by biological activity of the lungs. In another mode of operation, the electronic stethoscope disproportionately amplifies abnormal heart sounds and normal heart sounds to enhance diagnosis of heart abnormalities. The electronic stethoscope is operated in a manner similar to a conventional acoustic stethoscope and has similar spectral characteristics, thus allowing a user with acoustic stethoscope experience to easily use the electronic stethoscope.

Abstract: A stethoscope having a light source includes a stethoscope head and flexible tubing coupled to the stethoscope head and in communication with ear pieces for the detection and transmission of sounds from a patient's body. A casing is affixed to a cover of the stethoscope head and has a light source mounted therein. A switch is operable mounted on the casing for activating and deactivating the light source. Notches extend intermediate the casing and cover for grasping the same during use. A first end of the casing is disposed toward a perimeter of the cover and has an aperture through which light is emitted. The first end is adapted for mounting thereon various instrument heads as an otoscope or opthalomoscope. The first end may extend beyond the perimeter of the cover for mounting thereon the instrument heads. In an alternative embodiment, the casing is detachably secured to the flexible tubing of the stethoscope.

Abstract: A stethoscope provided with two conducting tubes and sound sensors, and two 3-way stopcocks; enabling the sound from one sensor to be conducted to one ear, while that from the second sensor is conducted to the other ear. One of the conducting tubes may be detached when the stethoscope is used for monophonic auscultation.

Abstract: An acoustic conduit includes an outer tube and two independent inner tubes. The outer tube is formed of a first material having a first density. The inner tubes are formed of springs of a second material having a second density and each creates an acoustic chamber. The first and second materials are chosen so that the second density is greater than the first density. The acoustic conduit may be used as, for example, a stethoscope tube.

Abstract: A stethoscope is fitted with a disposable cover to prevent cross contamination between patients. The cover is formed as a shield of material which is impermeable to liquids but which transmits sound waves. Adhesive is applied in a predetermined pattern on a portion of the cover so as to define a non adhesive fluid pathway between the central portion of the cover and its peripheral edge. This pathway adapts the cover for use with stethoscopes having vented diaphragms. Additional cover configurations are provided for use on the bell of a stethoscope.

Abstract: A stethoscope has a dual-sided stethoscope head. The stethoscope head includes a body member having first and second opposite sound collecting sides. Each of the first and second sound collecting sides has a suspended diaphragm member. Preferably, one side is specially adapted for use with adult patients while the other side is specially adapted for use with pediatric or thin patients where it is difficult to obtain good surface contact.

Abstract: A stethoscope includes a tubing having a first end to which an adapter is releasably mounted and second ends to which a pair of binaurals are mounted and a plurality of chest pieces selectively and interchangeably connected to the adapter. Each of the chest pieces has a tubular portion with a sound channel formed therein. The chest piece has formed on the tubular portion a guiding slot extending axially and a holding slot extending circumferentially and in connection with the guiding slot. The tubular portion of the chest piece has a deep recess formed on the holding slot. The adapter has a bore to receive the tubular portion of the chest piece therein.

Abstract: A stethoscope with a chestpiece which has two microphones oriented at a very obtuse angle to each other. The user of the stethoscope can switch from one microphone to the other with just a slight tilt of the hand. In preferred embodiments, no special action needs to be taken to activate the selected microphone as merely touching it to the patient's body selects it for activation.

Abstract: A stethoscope chestpiece is disclosed having an acoustic-to-electrical transducer residing within the acoustic pathway of the chestpiece. The transducer resides within a mounting that can provide shock attenuation and vibration isolation. The transducer preferably resides within a coaxial position in the acoustic pathway. The chestpiece is useful in a stethoscope which can be electrically connected to auscultation systems.

Abstract: A stethoscope device assembly which is adapted to monitor a surface sound on a body surface of a mammalian body and includes an earpiece assembly which is acoustically coupled to a sound receiver assembly. A sound transmission member is coupled to and extends between the earpiece assembly and the sound receiver assembly. An arm which includes at least a portion of the sound transmission member and also a superelastic member is coupled to and extends between the earpiece assembly and the sound receiver assembly. The superelastic member has a resting shape, such as a helical shape, which is adjustable under an applied force to a strained shape, and also has an elastic memory to the resting shape after being adjusted to the strained shape.

Abstract: A stethoscope with an indexing detent comprises a hollow body, a rotary tubular shaft, a and an indexing detent. The hollow body comprises two different microphones and a plurality of openings with the same diameters as that of the microphones. The rotary tubular shaft can be rotated around the hollow body, and it further comprises an axial hole whose central axis is aligned with that of the rotary tubular shaft, and a plurality of circular through holes at the locations related to the openings. On one of the circular through holes, there is a lock ball. Inside the rotary tubular shaft, there exist a resilient element which pushes the lock ball outward. When the circular through holes are directly aligned with the openings, the lock ball is pushed outward by the compressible resilient element and then partially goes into one opening to lock the related locations of the rotary tubular shaft and the hollow body.

Abstract: A stethoscope for reducing background noise comprising a housing having a receiver portion and an audio output means; the receiver portion having a plurality of noise ports; a microphone isolator located within the receiver portion; a noise canceling microphone having a front end and a back end enclosed by the microphone isolator; an acoustical tube having an acoustical waveguide connected to the microphone isolator for channeling an input signal; a chest piece having a sound diaphragm pickup for receiving the input sound and noise signal connected to acoustic tube to permit a pressure gradient noise porting placed at the back end of the microphone and internally behind the noise port.

Abstract: A device which is designed to simultaneously store and sterilize the head of a stethoscope within the pocket of a user during periods of non-usage. The small sterilizer is a box-shaped unit constructed of glass and plastic which fits into a shirt or jacket pocket, and which has a U-shaped lip which leads into an opening for receiving the head of the stethoscope. Beneath the lip is a switch that operates on contact with the stethoscope head to activate the unit, and the unit is powered by a small pen light batteries. An ultraviolet light is located proximate the U-shaped lip and delivers ultraviolet light rays through a circular transparent window aligned with the stethoscope head, and a clip on the back of the unit enables it to be easily attached to a user's pocket.

Abstract: A stethoscope includes a Y-shaped metal tube, a pair of binaural tubes, a pair of resilient tubes and a Y-shaped rubber tube. The metal tube has a main tube section and two branch tube sections connected to the main tube section. Each of the resilient tubes has two opposite ends which connect a distal end of a respective one of the branch tube sections to a distal end portion of a respective one of the binaural tubes. The rubber tube has a first tube section which confines the main tube section and two second tube sections connected to the first tube section. Each of the second tube sections is sleeved onto a respective one of the branch tube sections, a respective one of the resilient tubes and the distal end portion of a respective one of the binaural tubes in order to conceal the Y-shaped metal tube and the resilient tubes in the Y-shaped rubber tube.

Abstract: A mechanical system for reducing unwanted vibration of a stethoscope chestpiece, which reduces the signal components of the chestpiece output due to sources of vibration other than internal physiologic processes within the patient's body. The system includes a compliance, a mass, and a mechanical resistance element, which together increase transmission loss of external sources of vibration between their source and the chestpiece transducer. Methods of using such a system are also disclosed.

Abstract: A stethoscope includes a chestpiece with at least one sound gathering device, a binaural assembly with two earpieces, and a sound transmission unit between the chestpiece and the binaural assembly for transmitting auscultatory sounds from the chestpiece to the earpieces. The chestpiece confines an acoustic path therein. The sound gathering device is mounted on the chestpiece in acoustic communication with the acoustic path. The sound transmission unit includes a rigid first hollow connector which has a first end mounted on the chestpiece in acoustic communication with the acoustic path and a second end formed as a tubular wall, and a flexible second hollow connector. The second hollow connector has a sleeve portion and a pair of transmission tubes connected integrally at one end to the sleeve portion and mated with the earpieces at an opposite end. The sleeve portion is sleeved over the tubular wall and engages sealingly the latter.

Abstract: A stethoscope chestpiece is disclosed having an acoustic-to-electrical transducer residing within the acoustic pathway of the chestpiece. The transducer resides within a mounting that can provide shock attenuation and vibration isolation. The transducer preferably resides within a coaxial position in the acoustic pathway. The chestpiece is useful in a stethoscope which can be electrically connected to auscultation systems.

Abstract: A pair of handles removably secured to a stethoscope enable users to single-handedly mount and remove the headset to and from his or her head. By squeezing the handles together, a user can separate the upper ends of the rigid tubes of a stethoscope headset against the force of the biasing mechanism of the stethoscope. Each handle includes a channel configured to coaxially secure therewithin an ear tube and flexible tubing connected to the ear tube. A portion of the channel is configured to removably secure the ear tube and an adjacent portion is configured to removably secure a portion of the flexible tubing connected to the ear tube.

Abstract: The present invention relates to a low-cost, disposable, flexure sensor with an active portion which includes first and second sensor elements formed from a piezoelectric polymer material. Each of the first and second sensor elements has a first surface and an opposed second surface. A first electrically conductive area is formed on the first surface of each sensor element and is connected to a second electrically conductive area on the second surface. In a preferred embodiment of the present invention, the electrical connection is formed by a plated hole which extends through the sensor element from the first surface to the second surface. Still further, each of the first and second sensor elements has a third electrically conductive area on the first surface, which electrically conductive area is electrically isolated from the first electrically conductive area.

Abstract: An ear tip having a central portion and two end portions is described. The end portions each have ear contacting surfaces that are sized and shaped to contact the ear of the user. The ear tips are easily cleaned. The ear tips also contribute to user comfort and convenience.

Abstract: A protective cover for a contact surface of a stethoscope having a planar section of film material with a static charge placed therein. The planar section of film material has a top surface and a bottom surface. The section of film material has an area greater than the contact surface of the stethoscope. The top and bottom surfaces are non-adhesive surfaces. The static charge acts on the bottom surface so as to allow the bottom surface to removably cling to the contact surface of the stethoscope. The planar section of film material is applied to a backing surface having an area greater no less than the area of the section of film material.

Abstract: A stethoscope having a separable connection in the sound conducting tube permits the removal and attachment of various sound receiving portions. The connection has a first coupler attached to one free end of the sound conducting tube, and a second coupler attached to the other free end of the sound conducting tube. Each of the couplers is attached to the outer surface of the tube to avoid altering the inner diameter of the tubes in the vicinity of the connection. Maintaining the original diameter of the inner tube surface prevents adverse effects on the transmitted sound as it passes through the connected tube sections and reduces wear at the tube end. The first and second couplers are held together by suitable mechanical or magnetic attachment means that permit quick and easy separation of the couplers.

Abstract: A stethoscope includes a pair of binaurals and a chest piece with a rubber tube extending and connected therebetween. The chest piece has a body defining therein a cavity for movably receiving a frequency switching member which is movable between a first position and a second position. A retainer ring having a bore is fixed to the body to retain the frequency switching member within the cavity. The frequency switching member has a reduced end with a circumferential rib formed thereon extending through the bore of the retainer ring. The retainer ring has a circumferential rib which surrounds the bore and is in tight contact engagement with a membrane fixed to the body so as to define a first confined zone on the membrane which provides a first, low frequency vibration mode of the membrane.

Abstract: A removable and disposable chestpiece for a stethoscope. The chestpiece comprises a unitary disk-like chamber have opposed walls connected by a peripheral wall. One of the opposed walls is provided with a central opening. The head of the stethoscope is provided with an extending skirt which fits into the hole of the chestpiece.