David Littmann, M.D., (1906–1981) was a German cardiologist and Harvard Medical School professor and researcher[1]. The name Littmann is well known in the medical field for the patented Littmann Stethoscope reputed for its acoustic performances for auscultation.
With Gus Machlup, Dr. David Littmann founded Cardiosonics, Inc. to sell his stethoscopes. At that time the stethoscope line consisted of two key models, the doctor's stethoscope and the nurse's stethoscope.
3M acquired the stethoscope company on April 1st, 1967, and hired Dr. Littmann as a consultant. 3M currently produces the range of Littmann brand stethoscopes [2].