Ann: Results from Data Confirmation Study, page-273

They move the stethoscope around to listen to the heart, lungs, abdomen. Front and back, check where there's congestion / potential infection - in specific locations.
Resapp just listens to a cough, it's no wonder the most recent clinical trials have significantly different results to previous ones. It's comparable to listening to farts to determine stomach problems, there is simply not enough evidence in a cough with enough accuracy to make any meaningful diagnosis, other than, they have a cough.