Why does the narrator in 'The Tell-Tale Heart' finally give himself up to the police?

The neighbors called the police after hearing a shrike from the old man, the police search the whole house but don't find anything. Then, the narrator starts feeling a bit too cocky and places chairs right where he hid the old mans body in the floor, but he starts hearing a ring noise in his ears from the beating of the old mans heart (or at least that's what the guilt is described as) he gets so filled with furry that he tells them of the crime he committed.