But there is nothing to pick up those vibrations, therefore not making it a sound. The definition says that "vibrations that CAN BE HEARD WHEN THEY REACH A PERSON'S OR ANIMAL'S EAR
Tree
Alright, there wouldn’t be sound in the perceptual sense, BUT there would be a physical event, vibrations in the air and ground.
Falling tree exerts force on the ground and pushes through the air. By Newton’s laws, this force creates pressure waves, mechanical vibrations, in both air and earth. These vibrations occur independently of observation, making the event physically real whether or not anyone is present to hear it.
vibrations that travel through the air or another medium AND can be heard when they reach a person's or animal's ear."
so yes, the question is pretty much asking if it makes a vibration