This might serve as a good speech sample rip source for some of you, but that’s definitely not the creepiest. (And good luck recording anyone’s possessed voice and getting away with a ray of sunshine, while we’re at it.) If you want creepy and sinister, go hunt for number station recordings with child broadcasters – some of that stuff will leave you cold.
The “Enfield Poltergeist” was one of the most carefully investigated poltergeist cases of the last century. For more than a year the psychical researcher Maurice Grosse recorded hundreds of hours of interviews and apparent possession voices from the children at the epicentre of the activity. Janet in particular sometimes maintained the masculin sounding voice for hours at a time without any damage to her vocal cords and a speech specialist declared that what she was doing was not possible using her normal physical organs. When speaking she was “Bill” who had died in the house.