There is a medical museum in Riverside that I've written about several times for Trevor's Travels. It is a tough look at how things really were back in the "good" old days. One exhibit is the advance of the stethoscope - an interesting short history.
It seems that the normal way of listening to a patient's
heart a couple of hundred years ago was simply to lay the ear on the chest, and listen.
Apparently one day an extremely well developed young lady needed attention. The doctor was somewhat flummoxed by the presented twin problems. In a fit of inspiration he grabbed a piece of paper from his desk and rolled it into a tube to keep his head away from the protuberances. It was not long before better tubes were developed and thence flexible ones.
I was told this by the custodian of the museum; I have no reason to doubt him, and it makes sense to me.