YSK that if your pets spook you out by regularly staring/whining at some random spot on a wall, they may be hearing water move through the plumbing, and not “sensing ghosts”
from /r/YouShouldKnow
如果你的宠物经常在墙上的某个随机位置发呆/鸣叫，把你吓坏了，它们可能是听到了水在管道中流动的声音，而不是 "感觉到了鬼"。