I cannot hear the dead. Usually.
Depending on the circumstances, the difference between a state of constancy and almost constancy can be vast. I guess that’s like “I am bound by gravity. Usually.” Or, “My mother is robustly sane. Usually.”

People often talk about seeing ghosts, and those stories area told in a way wherein the experience was frightening, but I have always been more unnerved about the idea of hearing a disembodied voice. Maybe for me, the veil between life and death seems thinner if a voice can cross it than if a body can be seen across the divide. I can see stars, billions of miles away. I cannot hear them.