referring now to the drawings wherein is shown a preferred embodiment and wherein like reference numerals designate like elements throughout the several views , there is shown in fig1 a front elevation view of a hybrid stethoscope representative of the preferred embodiment . in the preferred embodiment , the universal stethoscope amplifier consists of two specialized earpiece units 10a and 10b , a main unit 12 , and a pressure sensitive on / off switch 14 . the first earpiece unit boa as seen in fig3 is comprised of a housing 20 , a pickup microphone 22 , an output speaker 24a , an input lead 26 connected to the microphone 22 , and an output lead 28a connected to speaker 24a . the input lead 26 the and output lead 28a exit the housing 20 at the bottom of the housing 20 . the second earpiece unit 10b is identical but does not contain microphone 22 or the input lead 26a . housing 20 is formed so that a threaded receptacle 30 and a threaded boss 32 exist on opposite ends of the housing 20 . the receptacle 30 is disposed directly adjacent the microphone 22 , and boss 32 is situated adjacent to the speaker 24a . receptacle 30 and the boss 32 are constructed such that the user is able to unthread the existing earpiece 34a on the acoustic stethoscope and , via the receptacle 30 or a selected adapter ( not shown ), is able to thread the earpiece unit boa over the threads on which the earpiece 34a or 34b had originally been threaded ( on the earpiece - end 102 of the stethoscope 40 ). the earpiece 34a or 34b is then threaded onto the boss 32 . since the metal shaft diameter and thread pitch of stethoscopes may vary , several sizes may be provided , or alternatively ( or in conjunction ), adapters ( not shown ) may be employed where necessary , thus allowing earpiece unit 10a to work with a common , acoustic stethoscope . in a second embodiment as shown in fig4 an elastomeric receiver 100 replaces the female threaded input receptacle 30 and allows the earpiece unit 10c to be removably received , via a pre - fit , directly onto the hollow metal tube 101 on the earpiece - end 102 , after having first removed conventional earpiece 34a or 34b . an annular boss 108 may also be provided to help align and stabilize the metal tube 101 on the earpiece - end 102 . in this alternative embodiment , the earpiece portion 104 of the earpiece unit 10c , which fits into the external auditory canal of the user &# 39 ; s ear is either integrally molded as part of the housing 20c of the earpiece unit 10c or otherwise attached thereto . the conventional earpieces 34a or 34b are simply no longer needed . this second embodiment thus enables ease of installation ( the leads 26 or 28a or 28b do not need to be removed while the unit 10c is attached to the hollow metal tubing 101 on the earpiece - end 102 ) and provides further universality because the elastomer of the elastomeric receiver 100 will compensate for different shaft sizes and thread pitches yet still maintain concentricity with the microphone 22 . in still a third embodiment substantially identical to that shown in fig4 the earpieces 34a and 34b need not be removed ; rather , the elastomeric receiver 100 is sized to receive either conventional earpiece 34a or 34b instead of the metal tubing on the earpiece - end 102 , thus increasing the universality of the universal electronic amplification assembly by taking advantage of the fact that the size and shape of a conventional earpiece 34a or 34b is more universal that the size and pitch of the metal tubing 101 and the pitch of the thread on the metal tubing on the earpiece - end 102 . a pressure sensitive on - off electric switch 14 ( normally in the off position ) is placed on the chestpiece 36 of the acoustic stethoscope 40 . the switch 14 is tripped to the on position when a preset minimum amount of external pressure is sensed as the chestpiece 36 , to which the switch 14 is attached , is pressed against a patient &# 39 ; s body . the switch 14 is attached to the face of the chestpiece 36 , which normally comes into contact with the patient &# 39 ; s skin . in this manner , the operation of this switch 14 is automatic . the switch 14 is electrically connected to main unit 12 via lead 50 , and as mentioned above , operates to enable or disable inputs from the microphone 22 . referring now to fig5 the chestpiece - end of a stethoscope which has a swivel and / or interchangeable chestpiece - end 120 , a diaphragm 128 , a bell piece 130 and a swivel - point or a receiver portion 124 . in this embodiment , a simple on / off switch 122 is mounted at the pivot base or receiver portion 124 , thus replacing the pressure sensitive switch 14 . alternatively , the switch 14 is simply removed from the main unit 12 either and a jumper ( not shown ) is installed or another automatic bypass ( not shown ) is activated . the main unit 12 as shown in fig1 and 2 , consists of a main unit housing 60 and various input / output ports , as well as controls and indicators provided to interface with the user / physician . the main unit housing 60 comprises a power source 100 , an amplifier 90 and a graphic equalizer 92 ( schematically depicted in fig2 ). it should be emphasized that these need not be physically separate units , as such units can be interconnected on the same circuit board . now referring in detail to fig2 in which is shown an electrical circuit diagram , an input jack 62 and output jacks 64a and 64b , located on the main unit housing 60 . these jacks allow each earpiece unit boa and lob to be electrically connected to the amplifier and equalizer via input lead 26 and output leads 28a and 28b , as shown . also located on main unit housing 60 are a main power switch 66a , a power indicator light 66b for the electronics housed within main unit 12 , a balance control 68 to regulate the output signal of main unit 12 between the left and right earpiece units 10a and 10b , and any other external output , an equalizer control 70 to allow the user to alter the frequency composition of the output signal , a volume control 71 , an auxiliary output jack 72 to enable other parties to listen to the output signal or allow the external taping of the output signal , an auxiliary input jack 74 , and an associated switch 75 to allow a prerecorded source to be heard , or alternatively , allow the user to listen to an output signal from output jack 72 of another unit . in addition , input jack 76 is provided to make an electrical connection with pressure sensitive switch 14 by way of leads 50 &# 39 ; and 50 &# 34 ;. referring again to fig1 the means which attached the main unit 12 to a common acoustic stethoscope 40 may be comprised of any number of known methods , among these are fabric tabs having mating velcro (™) swatches or mating snaps sewn or otherwise attached to the fabric tabs . one method , as depicted in fig1 includes the use of a tab 80 attached to the outside of main unit 12 , and to which velcro (™) may be attached both to the underside of tab 80 and to the rear panel of the main unit 12 via adhesive backing ( not shown ). further , acoustic stethoscope 40 contains a fork 84 , which includes the acoustic passage between the earpieces 10a and 10b and the chestpiece 36 . a mating velcro (™) swatch , backed with adhesive , may alternatively be placed on fork 84 , rather than on the rear panel of the main unit 12 . referring again to fig3 an acoustic wavefront traveling into earpiece housing 10a or 10b , via receptacle 30 , impinges on microphone 22 which converts the wavefront into an electrical signal . referring now to fig2 the signal travels to an amplifier 90 , and then to an equalizer 92 , located in main unit 12 , via input lead 26 . the signal is amplified , equalized and returned to speaker 24a and 24b in earpiece unit 10a , and , as the case may be , 10b , via output lead 28a , and / or 28b . the electric output signal is then converted back into an audio signal where the user can listen through earpiece 34a or 34b , which is threaded onto boss 32 . this output signal is also made available to external devices through auxiliary output jack 72 . a prerecorded signal or a patch to a second device &# 39 ; s output jack 72 can be piped into auxiliary input jack 74 of the main unit 12 from which it is rerouted to the user &# 39 ; s ear when auxiliary input switch 75 is positioned so as to bypass inputs from the amplifier 90 and receive inputs from the external source via the jack 74 . this enables the selective input of phonocardiographic sounds which are received by an instructor or which are pre - recorded for the purpose of instruction , thus constituting one of several advantages of the present invention . further , it should be noted that when the pressure sensitive switch 14 is used , the auxiliary input switch 75 is optional , due to the automatic isolation of the microphone 24 and amplifier 90 when pressure sensitive switch 14 is not depressed . optionally , an analog - to - digital converter 94 , may be provided positioned roughly as shown in fig2 and connected to the analog output of the graphic equalizer 92 , thus enabling interconnection with a computer device which can display or chart the output on a screen or on some other graphical interface , thereby further enhancing the teaching utility of the present invention . thus , it is apparent that there has been shown and described above a universal electronic amplification assembly that can be used with the common stethoscope . however , various changes , modifications , and substitutions in the form and details of the present invention may be made by those skilled in the art without departing from the scope of the invention . accordingly , it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention .
the present invention is directed to an assembly used for modifying an ordinary acoustic stethoscope to an electronically amplified stethoscope . this assembly is mechanically married to a conventional stethoscope &# 39 ; s tubular structure . an earpiece unit which replaces the standard earpiece on the earpiece - end of the ordinary acoustic stethoscope , is positioned so the standard air column response of any ordinary acoustic stethoscope is picked up by a microphone placed inside this special earpiece unit , thus capturing the acoustic output of the parent stethoscope and transmitting it back to a preamplifier / amplifier and frequency equalizer unit . the electronic signal is then directed to a speaker located in the special earpiece unit for monitoring by the operator , or alternatively , such signal is directed to a number of other remote units for the purpose of facilitating teaching and learning .