The practical diaphragm stethoscope was developed and patented by Dr. Robert C.M. Bowles in 1894. The original version had a flat diaphragm chest piece that could be used with or without a short rod that screwed into the diaphragm in order to localize heart sounds. The chest piece could be connected to a typical Cammann type binaural ear piece or, alternatively, could simply be used by applying the ear directly to the hollow opening of the chest piece. In 1901, Bowles patented a version of this stethoscope that became the commonly used type in the early 20th century. The sole manufacturer of the Bowles stethoscopes in America during the first half of the 20th century was George P. Pilling Son Co. of Philadelphia.



A Pilling Special Bowles Patent stethoscope with original rubber tubing, circa 1901. The stethoscope belonged to Dr. William F. Muhlenberg, great, great grandson of Henry Melchoir Muhlenberg, the founder of the Lutheran Church in America. Dr. Muhlenberg was born in 1852 in Gettysberg, PA, attended Muhlenberg College and recieved his medical degree from the Unniuversity of Pennsylvania in 1872. He was a prominent surgeon who practiced in Reading, PA and was on the staff of Reading Hospital. Dr. Muhlenberg served as President of the Berks County Medical Society in 1883. He died in 1915 from Myocarditis in Reading. His stethoscope came from the estate of Dr. Muhlenberg's grandson, Dr. John Peter Gabriel Muhlenberg of Berks County, PA, whose namesake was his great, great, great, great uncle of one of George Washington's revolutionary war Generals serving with him at Valley Forge, John Peter Gabriel Muhlenberg son of Henry Melchoir Muhlenberg.

A Bowles combination stethoscope was patented in 1902. It had a diaphragm chest piece, which was intended to be used interchangeably with a Ford chest piece. This was the first type of combination bell and diaphragm stethoscope.

Pilling combination stethoscope, together          Pilling combination stethoscope,  apart                 Klagges combination stethoscope, together        Klagges combination stethoscope, apart

The photos shown above on the left are the Pilling version of this stethoscope, circa 1910. The stethoscope is displayed with the Bowles diaphragm chest piece separate from the Albion Ford chest piece and with the Bowles diaphragm chest piece inserted by a Bloomfield connector into the Ford bell, converting the stethoscope to a Bowles diaphragm model. The photos shown on the right are the Klagges model of this stethoscope, circa 1940. The stethoscope has plastic Ford bell and Bowles diaphragm chest pieces displayed in the same manner as the photos on the left. Note the metal cover that is clipped onto the Bowles chest piece to protect the plastic diaphragm when it is not in use for auscultation. 

At the turn of the century when membrane stethoscopes were coming into widespread use on binaural stethoscopes, the use of a membrane on monaural stethoscopes was distinctly unusual, although an early twentieth century Aesculap catalogue shows a metal monaural with a membrane cap that could be placed on or taken off the chest piece. Below is a unique example of a monaural membrane stethoscope.


Shown above is a unique monaural Membran Stethoskop and its original box made in Germany, circa 1920. The stehtoscope has a membrane that screws onto both inter-changealble chest pieces, as well as in the ear piece. The membranes are made of a clear plastic material (although they look black in the image). There is an anti-chill rubber ring that fits onto the rim of the chest piece as shown in the chest piece on the left. There is no makers mark on the stethoscope, and this sethoscope may have been made specially for an individual physician.

Also during the first part of the twentieth century, there was considerable interest in developing stethoscopes that differentiated the intensity of heart and lung sounds. Notable examples were the Diffrerential Stethoscope of Dr. O. Leyton and the Symballophone of Dr. William J. Kerr.

Lyeton Stethoscope             Lyeton Stethoscope           Lyeton Stethoscope          Lyeton Stethoscope

A unique Leyton Differential Stethoscope, circa 1918. Dr. O. Leyton based its design on the differential stethoscopes developed by H. Bock and M. Y. Oertel. The differential stethoscope was used to determine the relative intensities of heart sounds. The screw mechanism could be adjusted to allow for greater or lesser transmission of sound through the chamber and therefore record the intensity of sound. The stethoscope head shown on the two photos to the left was sold either separately or with binaural earpieces. The photos on the right show the original box that contained the stethoscope head and article with a description of the construction of the stethoscope and instructions on how to use the differential stethoscope.

William J. Kerr, M.D. was appointed the first full-time Professor and Chair of the Department of Medicine at the University of California San Francisco (UCSF) School of Medicine in 1927. He received his medical training at Harvard Medical School, graduating in 1915. Dr. Kerr's special interest was cardiolgy, in particular the use of instruments to aid the precise diagnosis of cardiovasular diseases. In 1937, he described "a modified stethoscope for the lateralization and comparison of sound" in the American Heart Journal and received a patent for his symballophone in 1940. In 1950, the Board of Regents released plans to build a new 12 story hospital and medical sciences building on the UCSF site overlooking Golden Gate Bridge. The cross shaped hospital was designed by architects Timothy and Milton T. Pfluger and named after the former Dean of the medical school, Herbert C. Moffit. Dr. Kerr convinced the California legislature to add funding for an additional 13th floor in the new hospital buiding to be held as a shell floor for future cardiovascular research. Thus when National Heart Institute funding became available, UCSF had available space and under Dr. Kerr's guidance a Cardiovascular Board dedicated itself to the creation of the Cardiovascular Research Institute (CVRI) on this floor. The floor plan of the 13th floor allowed multiple departments to work together as a single unit and established the importance of interdisciplinary research in medicine.


    William Kerr        Symballaphone document

William J. Kerr, M.D., circa 1940 and a photo of the document describing the use of the symballaphone that came with each stethoscope.

Case name      Symballophone Case       Kerr Symballophone, 1950                        Kerr Symballophone          Kerr Mechaniism    

The Kerr Symballophone was very similar to Alison's differential model, but used two diaphragm chestpieces rather than bell chestpieces. In addition, sounds from either chest piece could be heard in both ears so that the examiner could compare sounds emanating from differnt parts of the chest. On the right is the Kerr Symballophone, circa 1940. Note the metal chest pieces and close-up of the double-looping tube connections of the binaural earpieces, such that each ear could hear the sound from either chestpiece. On the left is an example of the Symballophone, circa 1950s. Note that the chest pieces are now made of light weight bakelike instead of metal and that the rubber tubes are very long, presumably so that disparate parts of the chest could be auscultated and compared. The close ups show the leather case that contained this Symballophone. The stethoscope was used by Dr. Willaim Faulkner (1896-1976), a thorarcic surgeon who was at UCSF during the tenure of Dr. Kerr's leadership of the UCSF Department of Medicine.

The bell chest piece was very good for hearing the low-pitched sounds of the chest, however, there was the need to hear higher pitched sounds during auscultation. The diaphragm chest piece employed a membrane over the bell that allowed the higher pitched sounds to come through but blocked out the lower ones. It started to be used around 1900 and became a standard part ofthe modern stethoscope. The earliest models were designed to function as a small phonendoscope and came in a pouch for easy portability.

Davidson stethoscope            Small phonendoscope

The early diaphragm models resembled the older bell models but had a rigid membrane covrering the bell. These micro-phonendoscopes were very popular in Europe in the early part of the 20th century. On the left is an Oertel model signed F. Davidson, London, circa 1905. The entire stethoscope is made of metal, including the flexible metal tubes, and came in a leather pouch. On the right is a similar Oertel design, but with rubber tubes attaching the ear pieces to the chest piece. It came in a canvas pouch, circa 1900.

Physician card            Oertel stethoscope             European Physician

This Oertel model stethoscope was used in the 1920s by the Dutch physician L.M.S. Lekkerkerker-De Jong in Hilversum, Holland. This same physician's card is shown on the left and the photo on right is a European physician from that period with an Oertel model stethoscope draped around her neck. Note in the photo that the Oertel has flexible ear pieces, while Dr. Lekkerkerker's Oertel has a folding binaural metal earpiece and the metal chestpiece has an anti-chill rubber cushion but not a diaphragm.

Bowles flat iron stethoscope             Bowles stethoscope             Bowles stethoscope              Bowles stethoscope            Bowles stethoscope

Examples of the Bowles stethoscope are shown above from left to right: Bowles Flat Iron Stethoscope in original wood box, circa 1898; Bowles Stethoscope in original wood box, large size, circa 1901; Bowles Stethoscope in original cardboard box, medium size, circa 1909; Bowles Stethoscope with extra hard rubber bell (with connector inserted into the bell) in its original wood box, circa 1915; Bowles Stethoscope in original cardboard box, circa 1930.


Bowles stethoscope design               Sample Bowles stethoscope               Bowles chest pieces

The Bowles chest piece was designed with concentric circular grooves to enhance transmission of sound from the diaphragm into the tube connecting to the ear piece. Shown above starting from the left is the chest piece with 1. metal protective cover clipped on, 2. plastic diaphragm in place and 3. plastic diaphragm removed to reveal the grooves. In the middle photo is a rare sales sample Bowles stethoscope in its original wood box that was probably made for an Atlantic City medical meeting (note the label on the top half of the box) in June 1909. The box is 5.5 inches long and 1.5 inches wide. The sample bowles stethoscope is only 5 inches long. Bowles diaphragm chest pieces came in midget, small, medium and large sizes and with one or two connection tubes. Shown above on the right are the midget two tube, medium (regular) two tube and large one tube size chest pieces .


Pilling stethoscope with bracelet               Sprague-Bowles stethoscope, 1926             Spraque-Bowles stethoscope             Rieger-Bowles stethoscope              Folding Rieger-Bowles stethoscope

From left to right are: Pilling Bracelet Stethoscope with metallic band for the arm and diaphragm button to facilitate measuring blood pressure, circa 1920; Early Sprague-Bowles Stethoscope incorpoarting the Ford bell and Bowles diaphragm into one chest piece with lever to switch between the two and Herschel clamp to adjust ear piece tension, circa 1926; Sprague-Bowles Stethoscope with a typical lever-valve to switch between the Ford bell and Bolwes diaphragm chest piece in original box, circa 1943; Rieger-Bowles Stethoscope with an improved lever-valve to switch between Ford bell and Bowles diaphragm chest piece, circa 1950; Rieger-Bowles Stethoscope with folding earpiece in original cardboard box, circa 1963.


Kehler stethoscope                 Kehler improved stethoscope                 Fleischer stethoscope               Fleischer  stethoscope localizing rod               Meridith Swivel Stethoscope

From left to right are: Kehler Stethoscope in original mahogany box, circa 1897; Kehler Improved Stethoscope with original cloth case, circa 1901; Fleischer Triple Head Stethoscope in original cardboard box and with cloth case, circa 1940; Fleischer Stethoscope with localizing rod screwed into the diaphragm, circa 1950; Meredith Swivel Stethoscope with faux tortoise shell diaphragm and bell, circa 1930.


Phonophore             Minature phonendoscope            Teske Stethonoscope             Pollard Stethoscope             Heart Beat Stethoscope

From left to right are: Phonophore Stethoscope with rubber anti-chill cushion, circa 1910; Minature phonendoscope with hinged localizing rod, circa 1920; Teske Stethonoscope in original leather case, circa 1930; Pollard Stethoscope with tension screws to adjust the stretch of the diaphragm (missing), circa 1940;Pilling Heart Beat Stethoscope with tension adjustment of the diaphragm (missing), circa 1930. 


Cardiac clinic exam
             Cardiac clinic exam

A photo on the left of the Cardiac Clinic at the New York Post Graduate Medical School and Hopsital (now Tisch University Hospital of NYU Medical Center) is shown with a physician standing who is using a ford bell stethoscope to auscultate a patient's heart and another physician sitting who is taking the blood pressue of a patient, circa 1910. On the right is a glass lantern slide with a label that reads  "Doctor using stethoscope to listen to patient's heart; nurse making record on chart. Cornell Med. Center, NY" circa 1911.
( NYU Photo courtesy of the NYU School of Medicine Archives )

He found that costs remain high despite the expiration of 1960s-era stethoscope design patents, and so gathered Glia's team of hackers and hardware boffins to build the 3D-printed device.

It cost about US$10,000 to develop, and has been released as an open source model for anyone to use.

Western Electric stethoscope        Instructions                  RCA electronic stethoscope                   Faraday Sonoscope

The left photo is a Western Electric "3A" Stethoscope, circa 1925. The device was portable (14 lbs) and the volume and fliter of ascultatory sounds could be adjusted by turning knobs on the amplifier panel. The photo shows the chest piece to the left of the case and the to the right the Y attachment for a binaural ear piece. A second "consultant" could also listen. The instructions for use of this electronic stethoscope were given on the plate on the inside of the cover which is also shown above. On the right is a RCA "Acoustic" Stethoscope, complete with instructions and technical information, circa 1943. The Faraday "Sonoscope" is shown on the far right in its wooden box and came with instructions and technical information, circa 1956.


Rappaport-Spraque stethoscope

Rappaport-Spraque stethoscope

A Sanborn Company and Hewlett Packard Rappaport-Sprague binaural stethoscope set that dates to the early 1960s.  The chestpiece is marked:  RAPPAPORT / SPRAGUE / STETHOSCOPE // SANBORN / COMPANY / WALTHAM / MASS, U.S.A.  The set includes a wallet marked HEWLETT / PACKARD / SANBORN / DIVISION, that holds chestpiece fittings and two sets of additional earpieces.  Hewlett Packard took-over the Sanborn Company, of Boston, in 1961 and changed its name to the Sanborn Division.  While HP produced the Rappaport Sprague for the next 40 years, the Sanborn Company was the original maker, following the design of Dr. Howard Sprague, a Boston cardiologist, and Maurice Rappaport, an electrical engineer and acoustics expert at Sanborn.  This instrument is one of the first of the Rappaport Sprague stethoscopes to be sold by HP, but is housed in its original Sanborn cardboard box. These stethoscopes were considered the finest acoustical instruments made for auscultation in the 20th century.  
(Photos courtesy Alex Peck)

Dr. David Littmann was a distinquished cardiologist and international authority on electrocardiography. In 1961 he described the "ideal" stethoscope in the Journal of the American Medical Association . The stethoscope included an "open chestpiece for the the appreciation of low-pitched sounds, a closed chestpiece with a stiff plastic diaphragm to filter out low-pitched sounds, firm tubing with a single lumen bore, the shortest practical overall length, a spring with precise tension to hold the ear tubes apart, and light and convienent to carry and use." The Littmann Stethoscope was referred to as a "two-sided chestpiece" stethoscope and was originally made by a small, Cambridge Massachusetts company, Cardiosonics. There were two models, the doctor's stethoscope and the nurse's stethoscope. The Littmann Stethoscope rapidly became the stethoscope of choice in America and its simple design is still the basis for most stethoscopes used in medical prcatice today.


Littmann stethoscope                                                             Littmann stethoscope box

David Littmann, circa 1961. Note the Littmann stethoscope hanging from his neck in the photo.
On the left is the original Littmann stethoscope, circa 1961. The use of stainless steel and firm tygon (instead of rubber) tubing made from plastic enabled the manufacture of a model weighing only 3 onces. On the right is the original cardboard box that contained this stethoscope.
( Photo of Dr. Littmann from the Harvard/Roxbury VA Yearbook)

Ron Littmann, the grandson of Dr. David Littmann, provided this brief history of the development of the Littmann stethoscope below:

My Grandfather owned a house in Medford Mass where my father was born.  In his basement he had an old fashioned metal lathe he used to tinker with and where he created the stethoscopes and the chest pieces. Gus Machlup and his family fled Austria and came to America in 1939 to escape Hitler and the Nazi Regime. My Grandfathers house in Medford was like a duplex- split in half. He rented the other half to Machlup and his family. Gus was an entrepreneur. My grandfather was tinkering in his basement and he showed them to Gus and the rest was history. So as the story goes David created more and more out his basement and Gus convinced him that my grandfather wouldn’t have to put any more money in, Gus would foot the bill and they formed a business partnership to produce the Littmann stethoscope. David sold them out of his basement as Gus did the footwork. The cost back then was $25.00 per scope and if you bought 3 they were reduced to $18.75 each (no kidding). The scope caught wildfire and in 1961 together they had a production facility in Cambridge, Mass (Cardiosonics). The factory production was increased and it just took off from there. My grandfather was working on a special EKG lead of some sort when Cardiosonics was sold to 3M in 1967, and they continue to produce the Littmann stethoscope today.


On the left is the prototype of Littmann stethoscope, circa 1960, made by Dr. Littmann in the in the basement of his house. Note there are no markings on the stethoscope head. To the right is the prototype of the first 3M Littmann stehtopscope circa 1967. Note the marking 3M Littmann on the stethoscope head.
(Stethoscopes obtained from Ron Littmann)

The mechanism to hold binaural ear pieces in place has been a constant challenge in the development of the modern stethoscope. One very interesting mechaism was developed a relatively short time ago and represents the continued ingenuity that has characterized the development of the stethoscope throughout its long history.

Pope stethoscope               Pope stethoscope box

In 1980, a newly licensed Psychiatric Technician often had to struggle with agitated patients while trying to get his stethoscope in place in order to take vital signs. He adapted the Littmann stethoscope and devised a binaural headset tension mechanism to effect a scissor type action such that the stethoscope could be grabbed with one hand and squeezed as shown on the cover of the stethoscope box, which enabled the two tubular parts of the ear piece to be opened and easily put on or taken off the ears. This then 22 year old innovative young man, Janson M. Pope, Jr., sent me his stethoscope shown above ( Stethoscope with One-Handed Headset Operation, USA Patent # 4406346, September 27, 1983 ).

Dr. Tarek Loubani, an emergency physician working in the Gaza strip, developed a 3D-printed stethoscope as part of a project to bottom-out the cost of medical devices. Loubani together with a team of medical and technology specialists designed the stethoscope and tested it against global standard benchmarks, finding it performed as well as the gold-standard Littmann Cardiology 3 stethoscope, which served as the basis for the 3D design. The Glia project was born in 2012, where Loubani and his medical colleagues were in short supply of the life-saving equipment and forced to listen to the heartbeats of scores of Gazans with ears placed on chests (Immediate auscultation). Dr. Loubani says the concept of the 3D-printed stethoscope was inspired after he tested his nephew's toy stethoscope and found it performed much better than expected. Since costs remained high despite the expiration of 1960s-era Littmann stethoscope design patents, Glia's team of boffins built the 3D-printed device, which has been released as an open source model for anyone to use and can be printed at a cost of $5.
Pictured above on the right are 3D Loubani stethoscpoes. On the left is a 3D printed stethoscope designed by an aspiring veterinarian at the University of Tennessee, bought online in 2017 from Shapeways for about $15.

In 2018, M3DICINE launched an "AI enabled" electronic stethoscope called Stethee. The device can be used like a traditional stehtoscope to auscultate patients, but also to amplify, filter and record sounds. The sounds can also be analyzed with an accompanying smartphone app. Its "Aida" artificial intelligence software is capable of providing insights about the recorded sounds in order to make approriate diagnoses, and even create a biometric signature for the patient based on gathered data. 


Pictured above on the left is the Stethee, and to the right in addition to the Stethee the accompanying blue-tooth earplugs to allow the physicin to listen to the sounds and smartphones and smartwatch which record and display the characteristics of the sounds.

A variety of twentieth century stethoscopes contained in their cardboard boxes with a label identifying the type of stethoscope and manufacturer are shown below.

Stethoscope boxes

The stethoscope became the hallmark of the physician and had a profound effect on the art of physical diagnosis. It remains today an indespensible diagnostic instrument. Although Laennnec invented his simple wooden cylinder stethoscope over 200 years ago, until recently the modern stethoscope did not show any significant acoustical improvement (Ertel PY et al. Stethoscope Acoustics: Transmission and Filtration Patterns. Circulation. 1966;34:899-909).

We hope you have enjoyed your tour of the history of the stethoscope. Please come back soon.

We are always interested in acquiring new items for the collection. If you have any items for sale or questions, please do not hesitate to contact us.