Re: Advice please on what mics for recording in quiet outdoor enviro

["Avocet" madl74]

> The increasing interest in drones for police and hobbyists is likely
> increasing the pressure of anthropogenic presence on natural
> soundscapes.

John,

Rich hobbyists. :-)

At night I guess that they are trying out their thermal imaging
cameras, but don't ask too many questions.

> What affect would diffraction through trees in a forest have on
> frequency of an object passing overhead?

None. The average frequency as shown on a power spectrum drops due to
the Doppler effect as the object passes. Birds are unlikely to be
flying at over 110mph, assuming that the prop frequency was constant 
which is reasonable.

Last year I calculated the speed of a motorbike overtaking me on a 
narrow country road at 140mph, from the Doppler effect. The general 
speed limit is 60mph and I was doing 50 and looked as if I had my 
handbrke on.

David

David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce