as embodied and broadly described herein , the present invention is directed to novel electronic stethoscopes for diagnostic auscultation of body structures . conventional stethoscopes are designed to detect sounds produced in the body . a conventional stethoscope contains ear pieces connected to the bell / diaphragm by a flexible tube for receiving sound . this stethoscope is generally satisfactory and reliable but its simplicity is also a significant disadvantage as many physiological sounds are reproduced without sufficient clarity to perform rapid and accurate diagnosis of the physiological precursor of the sound . the present invention comprises a conventional stethoscope and one that incorporates amplification and / or recording circuits possible with today &# 39 ; s electronics . electronic stethoscopes have been proposed to modify the physiological signal to produce an audible signal which has clarity and which more accurately reflects the original physiological sound . some advantages and disadvantages of several such electronic stethoscopes are described in u . s . pat . no . 4 , 528 , 689 . in such stethoscopes , diagnostic resolution is improved , treatment and intervention techniques can be better assessed and there is minimal patient inconvenience . many health care providers are accustomed to the conventional stethoscope and find electronic stethoscopes expensive , cumbersome , and difficult to use . however , the preferred embodiment of the present invention , the echo +™ stethoscope , maintains all the classic features of a conventional stethoscope . in addition , the unit is capable of automatically adjusting the intensity of the auscultated sounds to optimize proper analysis by the user . the unit also captures ( records ) auscultated sounds which can then be replayed . these recorded sounds , can be replayed in one of two modes . the first mode reproduces the sounds just as recorded , thus allowing repeated analysis by several users . the second mode plays the recorded sounds back at a reduced rate , thus optimizing their analysis . the recording feature of the echo +™ is especially useful when examining easily distressed patients such as the crying neonate . by capturing the auscultated sounds before the patient becomes irritated a more accurate analysis can be performed . the recording feature offered by the echo +™ also provides a practical and convenient method of assessing patient progress . by comparing pre - treatment and post - treatment auscultated sounds the echo +™ can be used to gauge the success of treatment . in the teaching setting , the advantages for the student and patient are obvious . students can replay the auscultated sounds over and over without repeatedly reexamining the same patient , thus minimizing patient inconvenience . additional advantages offered by the echo +™ stethoscope include transferring of information for consultation , capturing the most appropriate auscultation environment , maintaining the familiar classic features , improved murmur detection and analysis . in addition to the above , the echo +™ offers improved conventional stethoscope resolution through improved acoustic chambers . the flexible metal conduit connects the housing to the ear pieces while maintaining a superior acoustic chamber . this conduit also maximizes external noise isolation and promotes self straightening and anti - kinking properties . the ear pieces have also been redesigned for better fit and longer useful life . in the following detailed description of the preferred embodiment , reference is made to the accompanying drawings which form a part hereof , and in which is shown by way of illustration a specific embodiment in which the invention may be practiced . this embodiment is described in sufficient detail to enable those skilled in the art to practice the invention , and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the present invention . the stethoscope in according to the present invention is described in accordance with fig1 - 12 . the preferred embodiment of the present invention looks substantially like a conventional stethoscope externally . in a preferred embodiment , locking ring / tensioner 44 is constructed of stainless steel . construction of main body 35 is well known to those of ordinary skill in the art . diaphragm plate 41 is preferably a standard epoxy diaphragm plate used in most new stethoscopes . bell thermal isolator 42 and diaphragm thermal isolator 43 consist of a rubber ring stretched or molded over the stainless steel housing 80 is used to decrease thermal conduction and maintain a seal with main body 35 . main body 35 is constructed from medical grade stainless steel and may be of standard construction which is well known in the art . bell communication port 86 and diaphragm communication port 87 are circular holes in the main body positioned 180 degrees apart and are a standard part of the main body of many conventional stethoscopes . spool socket 88 is preferably a circular hole into which spool 90 may be housed . microphone 205 is preferably an omni - directional electret condenser microphone element . speaker 210 is preferably a standard miniature communications speaker . electrical rotating connectors 400 are constructed of a nylon outer insulator 410 and brass conductors 420 . battery holder 110 is designed to hold battery 115 , preferably a 6v lithium battery . anti - twisting device 125 preferably consists of two independent stainless steel tubes and a rubber o - ring . tubing 25 is preferably a bilumen ( 14 &# 34 ;- 16 &# 34 ;) neoprene tube . neoprene is used to eliminate cracking and age induced stiffness related with conventional pvc and latex tubing . compression spring 45 is preferably a standard stainless steel compression spring used to improve the acoustic chamber and to maximize external noise isolation . locking ring / tensioner 44 is constructed in such a way that it mates by screws or other suitable joining method to main body 35 and secures diaphragm 41 to main body 35 while maintaining a seal with the body 35 . locking ring / tensioner 44 increases or decreases the tension applied to the diaphragm plate 41 thus proportionally changing the resonant frequency of ( or tuning ) diaphragm plate 41 . the locking ring / tensioner 44 also houses diaphragm thermal isolator 43 ( which is a non - conductive rubber ring ) to decrease thermal conduction transferred to the body . bell thermal isolator 42 and diaphragm thermal isolator 43 are used to decrease thermal conduction and maintain a seal with the body . the main body of the stethoscope is constructed from medical grade stainless steel and houses bell communication port 86 and diaphragm communication port 87 , spool socket 88 , microphone 205 , speaker 210 , electrical rotating connections 400 , electronics 200 . it should be understood that these component correspond to a particular embodiment of the present invention and other components may be substituted within the scope of the present invention . bell communication port 86 and diaphragm communication port 87 , are selected by the user by rotating spool 90 , are positioned to provide through communication ( e . g . a continuous air space ) with the ear pieces 20 when in the conventional mode . in a preferred embodiment of the present invention the spool rotates independent of depression and release of spool 90 . the diaphragm communication port 87 is in communication with microphone 205 when in the electronic mode . spool socket 88 houses a stainless steel spring 70 and stainless steel ball bearing 67 , which are used to lock the spool 90 into bell communication port 86 or diaphragm communication port 87 . bell communication port 86 or diaphragm communication port 87 are 180 degrees apart . microphone 205 communicates with bell communication port 86 or diaphragm communication port 87 and provides input to the electronics . speaker 210 is a standard miniature communications speaker that communicates directly with the user &# 39 ; s ear canal when the user selects the electronic mode . electrical rotating connectors 400 function as : 1 - an on / off switch and 2 - a connection between battery 115 , housed in the battery holder 110 , and the electronics 200 housed in main body 35 . the smart switch comprises the spool 90 and the electronics 200 . when the spool is depressed the housing 35 and spool brass conductors 420 are aligned ( making contact ), which actuates the smart switch . if the connection is broken , without reconnecting within a few milliseconds , the unit returns to the conventional mode ( off ). if the connection is momentarily broken , i . e ., depressing spool 90 two or three times in a row , the smart switch interprets the signal and selects the appropriate response ( amplify / record , playback , slow playback ). fig8 depicts one embodiment of electronic circuitry consisting of microphone 205 , speaker 210 , battery 115 , and various electronic components . electronics consist of band pass filter 602 , automatic level control 604 , sound recorder / sound register 610 , tap switch 608 , oscillator 614 , and power amplifier 616 . electronics 200 ( fig5 ) are mounted and held in the stethoscope diaphragm . band pass filer 602 limits the frequency of the signal from microphone 205 to a low pass of 70 hz and a high pass of 480 hz . automatic level control 604 takes a given range of input signals and provides a constant level of ac output . thus , a weak and strong heart will sound similar in amplitude . for example , if a patient is obese , the heartbeat sound may be dampened by excess fat between the heart and the stethoscope . in this case , automatic level control 604 operates to boost the signal level to the constant level , i . e ., provides full gain . in contrast , when a patient is excessively thin , their heartbeat sound detected through the stethoscope may be very loud . in this situation automatic level control 604 operates to reduce the signal level to the constant level , i . e ., provides minimal gain . finally , when a stethoscope is in use , it may come into contact with objects , such as chest hairs , which cause loud &# 34 ; noise &# 34 ; signals . in this case , electronics 200 provide a muting function . sound recorder / sound register 610 is a standard sound recording circuit which can record sound and play them back at variable speeds including normal speed . sound recorder / sound register 610 , in a preferred embodiment , has a storage capacity of 1 , 048 , 576 words × 1 bit . thus the worst case record time is approximately 14 seconds . oscillator 614 generates a beep each time tap switch 608 is activated ( e . g ., positive position feedback ). power amplifier 616 increases the drive of the input signal such that it can drive speaker 210 . tap switch 608 decodes a series of activations ( taps ) into functions including amplified playback , and record . tap switch 608 also controls the power to the other blocks in such a way as to save power ( e . g ., recorder is not powered up when in amplify mode ). referring to fig5 , and 7 , the actuator spool 90 houses the through spool port 430 , washer 65 , screw 60 , battery 115 , spring 122 and rotating electrical connectors 400 , battery retaining cap 120 , speaker output 440 , and anti - twisting device 125 . spool 90 may contain other components and remain within the scope of the present invention . through spool port 430 is positioned in such a way that when spool 90 is in the conventional mode , direct connection with the ear pieces 20 exist . a female communication port ( e . g ., a quick connect female output jack 411 ) is incorporated into through spool port 86 . quick connect male output jack 700 provides a means of coupling the output of the stethoscope to an external device . when in the electronic mode ( fig5 ), the diaphragm communication port 87 is in communication with microphone 205 . speaker 210 is separated from the microphone 200 , thus eliminating feedback , while maintaining a connection with the ear pieces . battery holder 110 is designed to hold a 6v lithium battery and maintain a patent air canal . battery holder 110 is shaped such that air can pass in the axial direction between battery holder 110 and main body 35 . the user &# 39 ; s ear canal is continuous with the air canal between the inside of the main body and the ear pieces . the user &# 39 ; s ear canal is also continuous with the speaker 210 in the electronic mode ( fig5 ) and continuous with bell communication port 86 in bell mode or diaphragm communication port 87 diaphragm mode , when in the conventional mode ( fig6 ). a stainless steel spring 122 connected to the anti - twisting device 125 provides a compression force to hold the battery 110 into position . anti - twisting device 125 preferably consists of two independent stainless steel tubes and a rubber o - ring constructed in such a manner that they can rotate independently while maintaining an air seal . in addition to the preferred actuator , spool 90 , several different versions have been developed . referring to fig1 , the first alternative , a spool plunger isolator , separates microphone 205 from speaker 210 and ear canal while maintaining a through connection with microphone 205 . the through connection is selected by rotating spool 90 , 180 degrees . when the plunger is depressed it closes the ear canal through port and eliminates feedback . when released the ear canal through port is free to communicate with the selected port . as with the current actuator , rotating the ear canal through port 180 degrees selects the bell communication port 86 or diaphragm communication port 87 . the second alternative , a spool hex isolator , ( fig1 ) separates microphone 205 from speaker 210 and ear canal while maintaining a through connection for microphone 205 . the spool hex isolator consist of a hex with a distal blind hole and a proximal hole that connects with the tube . direct connection between the blind port is through one side only . depressing the actuator breaks the direct connection , thus isolating speaker 210 and microphone 205 . releasing the spool reestablishes communication between the ear canal and selected port . the remaining sides of the proximal hex port are used to provide a speaker through hole with the ear canal when in the bell or diaphragm mode . the remaining sides of the distal hex port are used to maintain a through hole with microphone 205 and selected port . rotating the spool 180 degrees selects the opposite port . the third alternative actuator , a fully automatic spool utilizing a miniature electric valve to separate the ports , has also been developed . this configuration eliminates the need to depress the spool to isolate various ports . when the electric valve is energized , speaker 210 and microphone 205 are separated while microphone 205 maintains communication with the selected port . the speaker maintains through communication with the ear canal . when the valve is not powered , direct communication with the ear canal and selected port exists . an alternative to the current spool configuration fig7 is the spool slot isolator fig1 . referring to fig2 and 3 , tubing 25 may be a bilumen ( 14 &# 34 ;- 16 &# 34 ;) neoprene tube . neoprene is used to minimize cracking and age induced stiffness related with conventional pvc and latex tubing . in addition , a stainless steel compression spring 45 is molded into the tube 25 to improve sound transmission and prevent collapse of the tubing . the compression spring 45 also acts to straighten the tube when in use and maximize external noise isolation . elastic bodies have certain natural frequencies of vibration which are characteristic of the material and boundary conditions . when tube 25 and spring 45 are acted on by a series of periodic impulses , body cavity sounds , that have a frequency nearly equal to the natural frequency of the tube 25 and spring 45 they are set into vibration with a relatively large amplitude . thus tube 25 and spring 45 configuration described maximize the phenomenon of resonance to provide a superior acoustic chamber . the configuration maximizes the loudness , pitch , and quality of the body cavity sounds while maintaining a flexible conduit to the ear canal . referring to fig4 and 9 , the stethoscope is assembled in a step wise sequence . spool 90 is secured to battery holder 110 . ( step 500 ) spool 90 with attached battery holder 110 secured into position is inserted into main body 35 . ( step 502 ) the spring 70 and stainless ball bearing 17 are placed into the spring holder ( not shown ). ( step 504 ) spool 90 is locked into position by washer 65 and screw 60 . ( step 506 ) battery 115 is then inserted into battery holder 110 and secured into position by battery end cap 120 which is fixed to anti - twisting device 125 . ( step 508 ) tube 25 is forced over the tapered barbed end of anti - twisting device 125 . ( step 510 ) electronics 200 are inserted into their appropriate positions within main body 35 and secured into position . ( step 512 ) thermal isolator 42 is secured to locking ring / tensioner 44 . ( step 514 ) diaphragm plate 41 is placed between the main body 35 and locking ring / tensioner 44 . ( step 516 ) once aligned , the locking ring / tensioner 44 is secured to the main body 35 . ( step 518 ) bell thermal isolator 42 is secured to main body 35 . ( step 520 ) fig5 depicts spool 90 and main body 35 in electronic mode . fig6 depicts spool 90 and main body 35 in conventional mode . fig7 depicts spool 90 in greater detail . depressing the spool opens and / or closes bell communication port 87 in bell mode or diaphragm communication port 85 in diaphragm mode allowing the classic and electronic features to coexist without feedback . referring to fig5 electronics 200 may be constructed of standard electronic chips or a combination of miniature hardware and software or other electronics suitable for performing the necessary functions within the given space limitations . referring to fig8 band pass filter 602 isolates pathological and physiological frequencies . sound recorder / register 610 responds to tap switch 608 which includes an off , on # 1 , on # 2 , on # 3 setting , which refers to off - amplify , playback , slow playback , and record respectively . electronics 200 adapted for recording , allows for playback / slow playback of heart sounds while maintaining classic features of passive acoustic conduction . each new recording will erase the previous recording . the echo +™ utilizes a hard flexible tube and three methods of noise reduction when in the electronic mode . through electronics 200 the user is able to physically remove him or herself from a noisy environment . after recording , in a noisy room , the user can simply move to a quiet room for playback . the second method relies on the band pass filters in electronics 200 to attenuate frequencies above 470 hz . speech in the range of 2000 to 4000 hz is filtered very effectively through the band pass filter . the third method of noise reduction makes use of destructive interference and superposition principles . this feature is available only in the real - time amplify mode . through electronics 200 , two different signals are produced . signal one , consisting of pure body cavity sounds and external noise transmitted into the body cavity is filtered and amplified . a second signal representative of the external noise is inverted , filtered , and attenuated . the two signals are then allowed to destructively interfere with one another in the acoustic chamber . the net result of the destructive interference produces a third signal that represents pure body cavity sounds , i . e . unwanted noise is removed . this improved signal is transmitted to the ear canal through the flexible hard tube . quick connect female output jack 86 allows playback of recorded heart sounds through external speakers or transmission over telephone lines . an embodiment of the present invention provides real time amplification in one unit that reproduces as exactly as possible at the users ear the sound pressure signals originating from a conventional diagram or bell type of chest piece . an additional embodiment utilizes a signal processing approach which adjust the amplifier gain control to improve diagnostic resolution . microphone 205 detects audible sounds from patient and produces an output signal representative thereof and a variable gain amplifier 260 amplifies the output signals from microphone 205 to the speaker 210 . the acoustic chamber , consisting of spring 45 and tubing 25 improves sound quality by providing less signal distortion and decay in signal amplitude than is typical experienced in conventional stethoscopes . amplitude is maximized through resonance of spring 45 and tubing 25 , thus providing less decay in amplitude than a conventional stethoscope when in conventional mode . additionally , in slow playback the output is modulated to extend playback thus providing a slowed down version of the original sound , e . g . a slower heart beat without changing the quality of the sound as perceived by a health care provider . other embodiments and uses of the invention will be apparent to those of ordinary skill in the art from consideration of the specification and practice of the invention disclosed herein . all u . s . patents and other documents cited herein are hereby specifically incorporated by reference . the specification and examples should be considered exemplary only with the true scope and spirit of the invention indicated by the following claims .