Can religious fervour be inspired by low-frequency sounds from organ, or even drainage, pipes? Christopher Wood takes a spine-tingling look at infrasound

Some of the world's great thinkers have speculated on the origins of religious feeling, but recent work has suggested a rather unlikely explanation: the low-frequency, inaudible sounds created by long organ pipes, also known as infrasound.

The mood-altering effects of infrasound came under scrutiny recently at an open rehearsal at Liverpool's Metropolitan (Roman Catholic) Cathedral, part of the Sciart and Science on Stage and Screen Symposium - "sciart" being an initiative launched by the Wellcome Trust in 1997 to foster collaborations between scientists and artists. The event was designed by Sarah Angliss who, with a degree in electro-acoustic engineering as well as a diploma from the Royal College of Music, has the classic profile of a sciartist.

"It started off as a bit of a joke," she says. "We thought it would be the ultimate scam - a concert where nobody could hear anything - and of course you wouldn't have to do any work. But then I started reading round the subject of infrasound, and that's when I really got into it."

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Angliss found that infrasound cropped up in a surprisingly wide variety of contexts, from conspiracy theorists' claims that it was used during Vietnam war protests to quell riots to literature linking infrasound and ghosts. In a 1998 paper in the Journal of the Society for Psychical Research, investigators Vic Tandy and Tony Lawrence showed "how a 19Hz standing air wave may under certain conditions create sensory phenomena suggestive of a ghost". These include the flickering of candles without which no haunting would be complete.

And so to organ pipes, many of which emit infrasound along with the audible tones they are designed to produce. According to Angliss, exposure to infrasound and church-going have factors in common. "Infrasound has been described as causing a mild stress reaction. You're going to interpret that in different ways according to the context. If you're in a haunted-looking house and you get hairs standing up on the back of your neck, you're going to interpret that sensation in a very different way than if you're in a cathedral and the bishop's just said something about the power of God."

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Richard Wiseman, who heads a research unit at the University of Hertfordshire's psychology department and has led investigations into alleged hauntings at Hampton Court, agrees. "The interpretation depends on the context. What I want to know is, is the having of the experience entirely psychological? Do you walk in here, get struck by the look of the place, or is there some signal you're actually detecting?"

Angliss and Wiseman's experiment in Liverpool aimed to test whether infrasound could alter people's feelings. During a concert by the Russian pianist GeNIA at Liverpool Cathedral, a device resembling a supergun - in fact 10m of drainage pipe - periodically pumped out a stream of infrasonic noise. The audience had to assess their mood on four scales (happy-sad, aroused-sleepy, excited-bored, angry-calm) at four strategic moments during the concert, indicated by the raising of a coloured card. Any belief in the paranormal had to be declared. The audience was also asked which of the four key moments they thought was accompanied by infrasound, judging by whether they suffered any unusual mood swings or unexplained sensations.

Alas, most of them got it wrong. Angliss thinks this is due to the low intensity of infrasound used. "I think we were being a little too cautious because of the nature of the building," she says. When it is turned right up, things start to vibrate and there are definitely unsafe levels. "You can get the same effect as being exposed to high levels of audible sound, such as at a rock concert, but because you can't hear it you're unaware of the danger," she says.

Liverpool was just a trial, but future experiments are scheduled for London's Science Museum and Purcell Room next year.

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