For believers in the paranormal, unsettling sensations brought on by old buildings can be a sinister hint of loitering spirits. But new research points to a more mundane explanation: inaudible sounds from aged pipes and boilers.

Scientists investigated the impact of infrasound on a group of volunteers and found that even though it was beyond the range of human hearing, people were more irritable and levels of cortisol, the stress hormone, rose when the sound was switched on.

The finding suggests that even when people are unaware of the presence of infrasound, which can come from old pipes, boilers and ventilation systems in basements, the inaudible waves may still affect how they feel.

On its own, the effect is unlikely to persuade anyone that a house is haunted, but for the right person in the right situation – a believer in the paranormal in a gloomy old manor, say – the unusual sensation may fuel suspicions of paranormal activity.

“What infrasound may do is supply a bit of bodily discomfort that a ghost or haunting explanation can then attach itself to,” said Prof Rodney Schmaltz, a psychologist at MacEwan University in Canada, who investigates why people believe in pseudoscientific and paranormal claims.

“For someone who is not inclined to think in terms of ghosts, the same sensation would probably just register as a stuffy, uncomfortable old building. For someone who is already primed, it might feel like proof of a spirit or presence,” he added.

Previously, the researchers ran experiments at a local haunted house attraction, Deadmonton, to see whether playing infrasound, or sound waves below 20Hz, made people more scared as they passed through. The results were inconclusive, so the team devised further tests.

In the latest study, 36 volunteers listened to calming instrumentals or the kind of unsettling music played at haunted house attractions. Half the time, without the participants knowing, the researchers also played infrasound through hidden subwoofers.

Writing in Frontiers in Behavioural Neuroscience, the researchers describe how volunteers could not tell when the infrasound was on, but when it was, tests suggested they felt more irritated and annoyed, rated the music as sadder, and had higher levels of cortisol in their saliva.

“Whether they were listening to calming instrumental music or something more unsettling, the infrasound shifted their mood and their stress response in a negative direction,” Schmaltz said. “In plain terms, you cannot hear infrasound, but your body and your mood appear to respond to it anyway, and the response tends to be unpleasant.”

Larger studies are needed to confirm the effect, but Schmaltz suspects that infrasound can contribute to the “vague discomfort” some people report in houses they believe to be haunted. “They very likely don’t know what infrasound is, but they have been told they are in a haunted location, so they attribute the feeling of irritation to a ghost rather than the old, low rumbling pipes in the basement,” he said.

Chris French, an emeritus professor of psychology and the author of The Science of Weird Shit: Why Our Minds Conjure the Paranormal, said research into the impact of infrasound had had mixed results. He said it was “plausible” that feelings caused by infrasound may lead some people to perceive a place as “haunted”, but that might be all. “It may be a step too far to explain alleged poltergeist activity, such as objects flying off shelves, as resulting from infrasound,” he said.

“It’s also been claimed that infrasound may cause visual hallucinations such as apparitions by causing human eyeballs to vibrate. This speculation is based purely on anecdotal evidence and is not backed up by any evidence from properly controlled studies.”