Etymology is the study of words, where they originated, their derivatives and interpretations. Mostly in writings, so I don't think a stethoscope would make a useful tool.
What is the name of a person that studies derivation of
Depends : fingers, stethoscope, EKG.
The doctor used his stethoscope to listen to the sound of your heatbeat
This could be a linguist or an etymologist.
psychologist
Can be, to listen to stomach sounds.
A doctor can use a stethoscope for a number of functions. The primary function is to listen to the heartbeat of a client. The other is to listen to the patient's lungs.
A stethoscope.
stethoscope
A stethoscope
Stethoscope
a stethoscope