How Airtight is YOUR Stethoscope?
Take this test and see.
Turn the chestpiece so that you enable the bell (hole is under bell opening). Connect the stethoscope to your ears. Put one finger over the chestpiece bell hole to seal it. Lightly press on the diaphragm. Do you feel pressure in your ears when you press on the diaphragm? If so, the stethoscope is leaky.