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Why are some broadband routers emitting ultrasound?

AR Brearley

I'd recently been cajoled into changing ISP and having FTTP installed. The new ISP quickly sent out their router and I've had chance to test it for ultrasound emissions before having the telephone line replaced with a fibre cable. I did this knowing that I'd been in a house where my tinnitus was being stimulated and found that the broadband router positioned a few feet away, was emitting a sharp 21 kHz signal.

Here's what the ultrasound app I use revealed for the new ISP's router once it had completed its boot up sequence:

That's over 40 dB at 21.75 kHz, measured around 6 to 8 inches away. The ultrasound was being emitted by the router itself, not the power supply built into the mains plug a couple of feet away. When I'm exposed to ultrasound up to at least 30 kHz, it results in the perception of a high-pitched audible tone at approximately 14 kHz, my tinnitus tone, thanks to suffering from the "ultrasound hearing" phenomenon, as discovered previously. (See the discussion:Reasons why I suffered tinnitus, insomnia, chronic fatigue, and other health problems after having digital electricity meters installed ) (Also, I know the range as my dentist uses a 30 kHz dental descaler, painfully at times.)

Frequencies between 21 and 22 kHz are just over the top of the normal audible range for human hearing, particularly very young children, so for some people they may hear the exact tone. If these emissions are somehow accidental, then it may be possible that some routers emit sound just under 20 kHz. Cats and dogs have much more sensitive hearing than us and would have no problem hearing tones well over 20 kHz as normal sounds, probably very unpleasantly.

If you search online, you will be told that routers do not emit ultrasound, but this is clearly untrue. I've now found 2 out of the 4 I've tested doing so, subject to the microphone's limit of 22 kHz.

There's no purpose, at least not that I know about, for routers to emit ultrasound, so the simple question is; why?

  • 0 in reply to mapj1

    Hi Mike,

    I think we'd better issue a warning:

    Anyone thinking of opening up electronic devices and using things like mastic to cover components and block ventilation holes up to baffle any type of noise being generated, acoustic or ultrasonic, this may lead to overheating issues and hence be dangerous. This should not be attempted unless you are sure about what you are doing and of course, utility provided equipment like routers are the property of the utility and should not be interfered with. If you can gather enough evidence that utility equipment is causing you to hear noises that you should not be hearing, please complain to the utility and ask them to replace it. The more people who do this, the more likely action will be taken to stop such devices being issued and installed in the first place.

    There are at least 2% of the population with ultrasound hearing, that's 1.4m in the UK, most of whom will have routers, electricity meters and other electronic kit that incorporate these ultrasound generating switched-mode electronics in their design, that risks these people suffering from a combination of the symptoms I listed earlier, plus other symptoms if they are also electro-sensitive. (That's if ultrasound hearing is not considered a form of ES itself. It certainly indicates a higher risk.) Most of the people affected will not understand why they have acquired their symptoms and the medical profession will not be able to diagnose them let alone provide useful treatment. Hence, awareness of this problem is needed on all sides and the use of circuitry that generates hidden ultrasound at levels that can cause awful symptoms in humans and pets, ought to be stopped.

    I calculated the cost of fitting suppression in smart/digital electricity meters and compared it against the cost of the health care provided to myself during the time I had them in my home. (See:RE: Reasons why I suffered tinnitus, insomnia, chronic fatigue, and other health problems after having digital electricity meters installed) The health care costs for the minority affected is hugely more expensive compared to the cost of the suppression for all meters and there's no way I can put a cost to the utter misery caused by suffering the symptoms.

    Andrew

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