why does usher feel the house has become sentient

Well there is his creepy sister Madeline who suffers from a sort of catalepsy (a sickness involving seizures) . Usher believes his house is sentient (able to perceive things). He thinks it has power over both his sister and himself. This could be because Usher hasn’t left the mansion in years but he house is sure creepy. In the end the house falls a part with all the crazy noises going on.