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Forget infrasound, now it's ultrasound that's making you ill (allegedly)

Sick of health scares? So are we

Add gun-muffs to your tinfoil hat: the latest "stuff is making you sick" claim to garner headlines is about ultrasound.

In this paper in Proceedings A of The Royal Society, University of Southampton professor Tim Leighton says you're exposed to ultrasound pretty much everywhere, pretty much all the time.

You just don't know it because you don't hear it. That's what "ultrasound" is, after all: the stuff beyond the range of your ears.

Excitedly picked up by a bunch of outlets (Google News currently lists 71 articles), the paper reckons a complete re-write of noise exposure standards is needed to protect people.

However, exactly what we'll be protected from is less clear.

"The subjective symptoms reported by people (migraine, nausea, tinnitus, headaches, fatigue, dizziness, feelings of ‘pressure’) are so common and so non-specific that most clinicians are unlikely to attribute them to a physical cause," the paper states, adding "the lack of evidence means that adverse effects from airborne ultrasound are not included in any of the relevant NICE (UK National Institute for Health and Care Excellence) publications that support differential diagnoses ... reports are primarily anecdotal and vary from describing instantaneous responses to a 30-min delay before the onset of adverse effects and include reports of persistence of headaches etc. for hours after exposure has ceased."

(The combination of "primarily anecdotal" reports with "common and non-specific" subjective symptoms makes El Reg wonder if the paper isn't actually measuring Wi-Fi syndrome.)

The paper doesn't offer a mechanism by which sounds you can't hear can harm your health, merely noting: "This paper will proceed on the assumption that at least some of the complaints from the public are indeed caused by ultrasound in air."

The paper suggests people with iPhones or iPads could get appropriate apps and start recording the ultrasound around them.

Newer devices have microphones that respond to frequencies around or above 20 kHz, but the researchers note measurements are "unlikely to be reliable," and signal processing software can leave behind aliasing artifacts.

Youtube Video

In fact, although the university's video prominently features an iPhone, serious measurements used serious kit – a Brüel & Kjær microphone specified to 100 kHz with appropriate preamp in one setup, a PCB Piezotronics sensor in another, all calibrated to an IEC type WS3 reference microphone. ®

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