Thanks, very interesting. Basically the authors blast high-power (~92 dBA) ultrasound around 25kHz and hope that microphone non-linearities will overwhelm the audible signal.
replyThis will sure make all the dogs in 20m radius mad. Hence the solution for the stealth recorder -- bring a dog, then complain about the ultrasound jammer (or at least to be aware of a jammer)
From the paper, it looks like the authors did not consider safety of animals, only human hearing safety.
As someone frequently annoyed by those stupid bird/deer/insect ultrasound emitters I hope this doesn't become common, with my luck I'll be able to hear them.
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replyHow would this affect people with cochlear implants?
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