Re: stethoscope type
I bought a nice dual head stethoscope for listening to hives to check for deadouts mid-winter. I never had much luck hearing the bees in the hive, though. I found I had to give the hive a pretty hard knock to get the bees to buzz enough to barely hear it with the stethoscope, and then it was only briefly that I could hear them. The method didn't have nearly the sensitivity for detecting live bees that I was hoping for. I decided that the stethoscope method wasn't all that effective, and never used it again.
A thermometer inserted through the top entrance is a much better method.
(7th year, 10 hives, Zone 5b, 5500')