But....if there is a lot of air flow, that turbulence will mask it.
I have an end plug for the copper pipe and 'touch' the object, which then increases the noise level.
There are physician types of stethscopes, but never got around to checking that out. Maybe another Harbor Freight or Northern tool purchase...but mine is El Cheapo, as made from misc stuff laying around the garage....garden house, 1/2" copper water pipe, hose clamp and a plastic funnel shoved into the hose end as the ear piece....