How many hertz can kill a flying house insects.......
Ultrasound, even high peak power pulses, is quite safe for human beings, including the unborn ones.If you get a bug zapper, only 60 (electrical) Hz is required to kill a bug. If you try to zap a bug with sound waves, you could wind up zapping yourself.
You could, however, get a copy of that Chinese patent and swat the bug with it. That would probably be more effective.
taregg: Flying insects can be killed if they are irradiated by powerful ultrasound. The frequency necessary depends on the physical characteristics of the insect. The idea is to cause the insect's abdomen, for instance, to vibrate so strongly that it explodes, killing the insect. One way of doing this would be to generate an acoustic field that sweeps across a range of frequencies, from say, 40 kHz to 200 kHz, just as the above patent does. When the applied acoustic pressure waves resonate with the insect's body those bodily structures vibrate themselves into destruction. An analogous example is the breaking of a thin glass with a high frequency tone.How many hertz can kill a flying house insects.......
You seem to have missed the "sweeping of frequencies" technique. This method insures that the insect will be insonified by the correct resonant frequency, at least momentarily.An impossible task that is. Although there is a small chance of a "kill" frequency (or multiple combined frequencies) to exist it will only be valid for one exact fly, as small anatomical differences will require a totally different frequency.
As stated by ChrisVer a fly is not a clean material so a sound wave will bounce and be absorbed by any tissue with a different speed of sound, thereby easily reducing the chance of resonance. Like "resonating" a box filled with sand.
You seem to be contradicting yourself. The quote says there are no harmful effects below the recommended limits. That is not remotely the same as no risk from exposure to airborne ultrasonic frequencies to humans whatsoever.These passages from the above paper indicate no risk from exposure to airborne ultrasonic frequencies to humans whatsoever:
"For ultrasonic components above 20 kHz, the limits were set to avoid hearing damage in the
audible (lower) frequencies. One-third-octave band levels of 105-115 dB were observed to
produce no temporary hearing loss, and were therefore judged non-hazardous in respect of
permanent hearing damage."