A friend worked on that subject and I found it pretty cool:
Animals often hide, flee or avoid sources of human noise. But to what extent? Which species do it more? What noises disturbs the most? They made a camera + speaker device triggered by animal presence and observed their reaction.
Interestingly what animals tend to fear the most is the sound of humans chatting. They probably recognize other animals in human voices, but vehicle sounds seem to confuse them more, though still triggers vigilance reactions.
