The stethoscope was invented in 1816 because a doctor felt uncomfortable placing his ear directly on a woman's chest.

In 1816, French physician René Laennec was treating a young woman with heart symptoms at the Necker-Enfants Malades Hospital in Paris. At the time, the standard practice was immediate auscultation, which involved the physician placing their ear directly on the patient's chest. Laennec felt this was inappropriate given the patient's age and gender, and he also found it difficult to hear clearly due to the patient's body fat.Recalling an acoustic phenomenon where sound travels through solid objects, Laennec rolled a sheet of paper into a tight cylinder. He placed one end on the patient's chest and the other to his ear, finding that the heart sounds were actually much louder and clearer than before. He eventually replaced the paper with a hollow wooden cylinder about 25 centimeters long, which he called the stethoscope, derived from the Greek words for 'chest' and 'examine.'Laennec published his groundbreaking work, 'De l'Auscultation Médiate,' in 1819, detailing how different sounds in the chest correlated with specific diseases. His invention revolutionized diagnostic medicine by allowing doctors to hear the internal workings of the body non-invasively. The design was further refined in 1851 by Arthur Leared, who created the binaural version, and later by David Littmann in the 1960s, whose acoustic design remains the industry standard today.