> (I speak to the mosquitoes in danish, but don't bother. I'm not
> saying anything very intelligent anyway. After all, they are only
> mosquitoes...)
Hans,
But they are Danish mosquitoes. :-)
You've got an original observation here - very interesting.
The main mosquito hum came between 600 and 900 Hz, so I constructed a
steep band pass filter between these frequencies. The mosquitoes react
when your voice contains these frequencies, and not with other
frequencies from you.
Judging from the "Boo", their reaction time is less that 300ms,
corresponding to a distance less than 50 metres. You probably had a
pyramid of mosquitos above you formed by the warm air and CO2 rising
from you.
>From the BPF, it can be seen that they only respond to your voice
frequencies around the 750Hz point, or possibly harmonics, but the
effect is clear at 600 to 900 Hz.
Possible reasons for the change in wing frequency may be in the
formation process of the mosquito pyramid. Possibly they sense the
group moving and speed up as a result.
Unlike the other wildlife sounds, the mosquitoes sound as if they are
out of the "sweet area" of the stereo pickup, but it's difficult to be
sure with a nebulous sound like this.
If you get this effect again can you try pointing the mics upwards?
David
David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce
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