All human-made objects eventually become sentient, due to their contact with human life-force. However, due to the quantum nature of their existence, they are unable to move or speak when humans–though not other creatures–would detect them.
Non-human creatures such as fairies and trolls generally prefer to live far apart from humans, so as not to be tormented by the unceasing Babel of their objects.
Vampires, who must live among humans, construct sound-proofed boxes in which they rest as much as possible. This probably accounts for the belief that they sleep in coffins.