The stethoscope entered commercial production in the middle of the 19th century. It is among the early diagnostic instruments of medicine, the use of which expanded the range of information available to the physician but not the patient, increasing the authority of the former and the dependency of the latter. From page 136 of Paul Starr’s The Social Transformation of American Medicine:
The use of the stethoscope, as Stanley J. Reiser has observed, required the physician, at least momentarily to “isolate himself in a world of sounds, inaudible to the patient,” and encouraged him to “move away from involvement with the patient’s experiences and sensations, to a more detached relation, less with the patient but more with the sounds from the body.” These sounds the patient could neither hear nor interpret. Similarly, the other instruments that gradually assumed a place in the doctor’s bag reduced dependence on the patients’ statement of symptoms and increased the asymmetry of information.