In 1816 Laennec created a paper acoustic device as a stethoscope in order to examine the chest of a woman with cardiac symptoms. He listened to her heart by the technique he called "mediate auscultation". Laennec described his creation of the stethoscope instrument in The Treatise on Mediated Auscultation in 1821:

"I was consulted in 1816 by a young woman who presented some general symptoms of disease of the heart, in whose case the application of the hand and percussion gave but slight indications, on account of her corpulency. On account of the age and sex of the patient, the common modes of exploration being inapplicable, I was led to recollect a well known acoustic phenomenon, namely if the ear is applied to one extremity of a beam, a person can, very distinctly, hear the scratching of a pin at the other end. I imagined this property of bodies might be made use of in the present case. I took a quire of paper which I rolled together as closely as possible, and applied one end to the precordial region; by placing my ear at the other end, I was agreeably surprised at hearing the pulsation of the heart much more clearly and distinctly that I had ever been able to do by the immediate application of the ear."