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, and headaches.
Schools, railways stations, sports grounds, museums, libraries and swimming pools are all potential sources of exposure.
Scientists are 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.
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. Short-term solutions include wearing ear plugs,
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.