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.
This is really interesting to me from the angle of why do some species coexist with humans in suburbs, etc, but others are pushed aside by development. I'm sure there are many factors, but I think sound is a big one. I wonder if it's possible to teach a population of a skittish species to be comfortable with suburban life over a few generations.
The deers of Nara show that giving them food and protecting them is an easy way to achieve that.
I had never seen deers as aggressive as monkeys towards humans!
My mom learned not to feed deer as a kid: "it's really cute until there's no more carrots!"