ABSTRACT
Some ghostly apparitions seem to have been accompanied by noise: footsteps, door-handle rattlings, raps. Such noises suggest some sort of impact on two different senses at once: that of sight and that of sound. Many raps have been recorded by sound equipment. In 1972 the Toronto Society for Psychical Research, encountered rapping noises during their extraordinary experiment of 'inventing' a ghost. The raps recorded by the Toronto group are scientifically well authenticated and very convincing, but other paranormal raps have also been recorded and studied sonically. They all seem to show that such raps die away faster than ones created by normal physical knocking. With a coherent solid object, such as a ring, it might even be possible to remove the top thousand or so atoms using a dilute acid. It would be interesting to discover if the resulting denuded object still stirred notions in the mind of a psychometrist.
