Scientists say that a boom in public announcement systems, loudspeakers and automatic doors may be spawning an epidemic of ultrasonic sickness.

Even electronic devices designed to scare away mice and cats could be triggering symptoms such as nausea, dizziness, and tiredness, stomach pain, headaches and headaches.

The symptoms of ultrasonic sickness have traditionally been associated with workers using heavy-duty drills, welding tools and other industrial equipment.

A growing number of people are reported to be suffering from a condition called ultrasound sickness and researchers believe this may be due to a boom in the number of loudspeakers, automatic doors and electronic devices in out every day lives (stock image of a man holding his ears is pictured)

However, Southampton University researchers say that modern technology means that growing numbers of us are surrounded by ultrasound pollution in our everyday lives.

Schools, railways stations, sports grounds, museums and libraries are all potential sources of exposure.

Physicist Tim Leighton warned that children may be particularly sensitive to the phenomenon and said that existing safety guidelines focus on occupational exposure and are weak, outdated and need to be overhauled.

The inaudible ultrasonic hum of electrical appliances all around us (fridges in a supermarket pictured) could be having a previously unrecognised impact on our health. Researchers measured the background noise in a range of locations where people have complained of symptoms typical of ultrasound sickness

Laying out his case in a journal published by the respected Royal Society, he said: 'The heart of the matter is this: advances in the ability to market inexpensive commercial ultrasonic sources have led to their increased use, exposing large number of people.

'Many devices now deliver exposures that cannot be classed as occupational.

'For both policymakers and clinicians, the evidence base is inadequate to protect public health and discomfort is likely to be seen in the general population as a result of ultrasound in the air.'

THE SEEMINGLY SILENT PROBLEM The study found ultrasonic pollution in schools, museums and libraries, as well as in a swimming pool and a sports stadium. Suspect devices include modern public address systems, many of which are permanently switched on and emit ultrasound signals while seeming silent. Many automatic doors use ultrasound sensors, while ultrasonic repellent devices are popular with householders who have mice but don't want to lay traps and gardeners who want to scare away cats without harming them. Professor Leighton thinks waves confuse the delicate motion sensors in the ear, in much the same way as seasickness, causing symptoms including nausea, migraines and dizziness. However, his theory is unproven and others point out that we have safely lived with strip lighting, which also emits ultrasound, for decades. Advertisement

However, others said that ultrasound is 'very unlikely to harm health' and said such worries should be left to hypochondriacs.

Professor Leighton recorded the background noise in a range of public locations including a busy and popular library, train station, swimming pool, museum and school.

All were chosen because people who had spent time in them had complained of ultrasonic sickness.

Wherever he looked, he got readings above 20kHZ in frequency, putting them in the ultrasound range.

The professor said that despite the common wisdom that ultrasound is too high-pitched for humans to pick up, the range of human hearing is highly variable and around one in 20 of us is to be able to hear into the ultrasound range.

In any case, it may not be necessary to hear ultrasound to be made ill by it.

He is not sure how ultrasound may harm health but one possibility is that it disturbs the delicate balance sensors in the ear, confusing the brain and calling seasickness-like symptoms.

Writing in the Royal Society journal Proceedings A, the Professor Leighton, said: 'There has been a massive increase in deployment of devices that operate by placing ultrasonic fields in air in residential, recreational and occupational places.

'Those exposed are often in ignorance of their exposure and there is no monitoring of levels

The researchers took measurements of ultrasound in public places like libraries, a train station, a swimming pool, a museum and a school. They say electrical devices like PA systems can produce ultrasonic noise that is just beyond our limit of hearing but can be having an impact on our health

'Scepticism is always required when anecdotal reports of subjective symptoms are produced by members of the public, particularly when the public attribute the cause to something imposed on them – a wind farm, power cable etc.

'However, we must also be sceptical about scepticism: it is possible for some individuals to be particularly susceptible to certain agents, allergies being an example.'

The professor added that while there is no need to panic, anyone who is concerned can download an app to their smartphone and use it to detect if there are any ultrasound-emitting devices nearby.

While short-term solutions include wearing ear plugs, he believes that ultimately the government needs to address the issue.

Dr Martin Coath (CORR), a Plymouth University expert in hearing, said there is nothing wrong in calling for safety guidelines to be reviewed.

Public swimming pools (stock picture) were among the places where people most commonly report suffering from ultrasound sickness. The researchers say there needs to be more evidence conducted before controls can be put into place

However, much more evidence is needed before any controls are put in place.

Jan Schnupp, a professor of neuroscience at Oxford University, was more sceptical.

He said that while it is true there is a lot of ultrasound in the modern world, almost none will be able to penetrate the skin and enter the body.

As a result, it is likely to be more troubling to cats, dogs, rats and other creatures with highly-sensitive hearing.

He added: 'Billions of people have been exposed to ultrasound from fluorescent lights for many years and by and large living longer and healthier lives than their parents' generation.

'While the author is correct in saying that we perhaps know less than we ideally would like about ultrasound levels in our environment, we nevertheless do know enough to be able to be fairly confident that it is very unlikely to be a significant health hazard to humans.