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| Because there's nothing odd to hear. The makers claim ultrasonics, but call 3 kHz and 12 kHz ultrasonic (which to my ears didn't being until over 22 kHz) which might be ultrasonic to a senior citizen who has worked in a airplane factory running a rivet gun 40 years. http://www.deercrash.com/Toolbox/CMToolboxWhistles.pdf summarizes several reports and comes to the conclusion that deer can't hear at 12 kHz and that the 3 kHz whistles are almost as loud as ordinary vehicle noise (neglecting the noise of a gravel road).
In one test conducted in a refuge, there was less deer notice on the second pass with whistles than on the first vehicle pass with no whistle.
The general conclusion is that they have no effect, the extreme conclusion is that they are a scam, like magnets on fuel lines and water lines, and millions of loose change in Nigerian banks looking for a new owner.
Gerald J. | |
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