Hi Don:
Thanks for the physics. I have always enjoyed a healthy scepticism
regarding gadgets. My experience with deer whistles is connected with my
annual trips to the Portland Swapmeet.
These occur in early April and for years we have driven all day and night
(multiple drivers in a large van) direct to Portland through Jasper
National Park, Mt. Robson Provincial Park then down the Thompson River to
Kamloops and the Coquihalla Highway. All of this is in prime deer, elk and
moose country at a time when they are very active. After several close
calls, I tried putting the whistles on my van. That year, for the first
time, when we would come around a corner, the animals were already
scattering - rather than standing looking at us. We had no close
encounters and I have had none since. That was 8 years ago. I have no
scientific proof of the efficacy of these things.
I believe the whistles were developed in Scandinavia where an extensive
testing program proved their effectiveness. I don't have documentation.
Perhaps another lister has some facts. In the meantime, I will keep my
whistles and my caution! I use them on my cars and my bikes. I keep them
on by buying 3M industrial double-sided tape and by throwing away the junk
they are packed with.
John McEwen
>I studied acoustics and vibrations for 4 years in graduate school so I have
>always had an interest in the subject of applying high frequency to animal
>avoidance. There are ultrasonic transducers to drive away roaches, rats,
>gophers, mosquitoes, deer, and acoustic sources to attract fish! I have
>never seen any scientific or otherwise study showing the effect on the
>animal. The only rationale seems to be that humans seem to think that it
>ought to work. An ultrasonic whistle is suppose to call a dog but repel a
>deer. Go figure?!
>
> The acoustic response of human ears is roughly 20 Hertz to 20,000 Hertz, or
>so say the books. Actually, for most of us in our 40's and 50's it is
>closer to 40 Hertz to 12,000 Hertz. Our maximum sensitivity (below about 70
>db anyway), is about 3000 Hertz. So if you wanted to repel humans, a very
>loud 3000 Hertz tone might do it. (actually Rap music is more effective) If
>I apply this to deer, I'm not so sure that your car horn might be just as
>effective. (The frequency not the Rap music....maybe the Rap music would
>work on the deer too?!) In fact I've never seen any proof that the deer
>whistle is even emitting a sound. I hate to be such a sceptic but this is
>not something that the government or the Product Safety commission is going
>to check. How do you know that these things aren't just a shiny piece of
>plastic that do nothing. It should state the frequency and decibels of
>sound at a given auto speed. In fact, the frequency is going to be a
>function of your auto speed due to the doppler effect.
>
>
>Don Mathis,Ph.D.
>donmathis@lucent.com
>'61 MGA
>'37 Bentley
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