Did the Dead Talk on Friday the 13th?

The boy's hands shook as he was given the digital voice recorder. Steadied by his father, he spoke into the darkened crypt: "What's your name and how did you die?" The rest of us, huddling together in the cold, bit our lips.

The red light on the recorder blinked in staccato, perhaps as though someone was speaking – although the room was silent. The recorder was held aloft so that we could hear the playback. For a while, there was silence. Then, unmistakably—to most of our ears, at least—came the words: "get out".

It was Friday the 13th, and people had gathered in a 12th century church in Canterbury to witness a phenomenon which it is claimed allows the spirit world to communicate with the world of the living.

EVP, or "electronic voice phenomena", is said to be recorded speech of a spirit left on an ordinary tape player, unheard at the time, but audible upon playback at high volume. It occurs in recordings where there is a lot of background static, or "white noise".

"I need to find the middle road, I can't totally believe and I can't totally be sceptical. I'm out to find the truth," said Mark Turner, of Ghost Finders Scotland, who hosted the Ghost tour at the the Canterbury Tales Visitor Attraction.

"As soon as someone says it sounds like 'get out', it will do," said Dan Pride, a more sceptical member of the tour.

Another person—who claims to be a psychic—said she had heard the response to the boy in her head before it came through on the speakers.

"He's very angry," said Wendy Walker. "He thinks we are mocking him."

Later, Wendy herself asked if there were any spirits present whether they would offer a sign. As the tour waited in silence, a door slammed upstairs.

We paused in two rooms on the tour to ask questions to a tape recorder, and waited in silence to allow any "entities present" to speak on the digital recorder.

At the end of the tour the recordings were transferred to a laptop and put through a filter to enhance the sound quality. The content of the files did not appear to have been changed in the process.

Most of the recordings made in the church were mostly garbled, but one or two appeared to resemble short sentences.

The digital recorder that Mark used was the Panasonic RR-DR60, a model which he says was taken off the market three months after it was released in 1999 due to the level of complaints received from people claiming that it picked up "other" voices.

Dr Catherine Watt of Edinburgh University's Koestler parapsychology institute explained: "It is well-established that human beings are really good at finding 'patterns' in what is actually random noise.

"A good example is thinking you hear the phone ringing or 'hearing' your name being said when in a noisy environment (e.g. hoovering).

"I think EVP could be a similar phenomenon, particularly if you are told by someone else what words are being 'said'—so you know what to look out for and your brain works very hard to impose the appropriate patterns on the noise.

"I suspect that if people are not told what is being said, they would come up with different words."

Indeed, members of our Canterbury tour were told prior to going in that the previous group had been "told to get out."

Some of the voices available to download on the Ghost Finders website are incredibly garbled, and can only be made out with the help of a blurb underneath the link.

Professor Chris French, who chairs the Anomalistic Psychology Research Unit at Goldsmiths College, described this as 'top down processing', that is: "the influence of our knowledge, beliefs and expectations upon the interpretation of raw sensory input."

He said: "As you would expect, top-down processing has a greater influence when the sensory input is ambiguous and/or degraded (as with EVP).

"On first hearing it you may, if you are lucky, pick up the odd word. Once you know what you are supposed to hear, you will hear a long passage of coherent English very clearly. It isn't really there of course—it's top-down processing."

Mark Turner, of Ghost Finders Scotland said: "It is true that people's perception of what is being said can be different unless the voices are what we call 'Class A EVP' (the clearest form)."

Of the files available to download online there appears to be a distinction between those that are merely inaudible screams and those which can be clearly made out.

Professor French said: "Some of the really convincing examples of EVP are just real (living) voices unintentionally recorded."

When EVP first appeared, it was argued that the clearer examples of voices were merely recordings of stray radio waves.

But Mark Turner cited experiments which demonstrated that EVP still occurred in a Faraday Cage—an apparatus which cuts out all electrical and radio signals.

Tom Butler, Director of the American Association of EVP (AA-EVP) and a sound recording expert, said that: "Stray radio waves, delusion or unnoticed physical voices have all been questioned, tested and discarded as possible sources for the voices."

"What remains to be understood is the who, why and how of EVP."

The concept behind EVP was first explored by Thomas Edison in 1920 when he wrote: "If we can evolve an instrument so delicate as to be affected or moved or manipulated by our personality as it survives in the next life, such an instrument ought to record something."

In 1952 two respected Roman Catholic figures—Benedictine monk Father Pellegrino Maria Ernetti and physician Father Agostino Gemelli—picked up what they thought were the voices of the dead while recording a Gregorian chant.

Their work was falling behind, and Father Gemelli asked his dead father to help him. To his surprise they found on the recording a man's voice saying; "I am always with you and help you."

In 1959 Lavian documentary maker Friedrich Jurgenson was recording the sound of bird song when he picked up discarnate voices. He believed that the voices were merely stray radio waves, until later he heard quite clearly the voice of what he understood to be his dead mother say: "Friedel, my little Friedel, can you hear me?" His published findings later formed the first breakthrough in EVP research.

Later a disciple of Carl Jung, Dr Konstantin Raudive, built an instrument through which he recorded thousands of voices.

According to some researchers, Raudive's influence in the world of EVP is as strong as ever. Although he passed away in 1974, they claim that his spirit has been leaving messages on audio recordings, videos and computers.