The Answer is Blowin’ in the Wind
I have always been amazed of the extent to which animals (especially coyotes) can hear; so much so that I wrote an article for Predator Xtreme covering the topic. However, it only scratched the surface. What has amazed me even more than their hearing range is how well they can hear even in windy conditions.
I have long suspected that coyote ears can filter wind and pick out sounds even sounds at rather low sound pressure levels (SPL). This is not obvious and straightforward at first thought because coyote ears are more sensitive to noise. Certainly the wind on their ears would be even louder to them than us. Somehow this doesn’t affect them. Why? Is it their ability to control their ears and direction them to maximize the signal? Perhaps. Is it related to their ear shape and construction? Very likely. However, today I would like to offer another suggestion, one that’s related to the aforementioned conjectures.
Wind hitting your ear makes noise. This noise has a frequency spectrum associated with it. If one were to compare the audible range of a predator with the frequency spectrum of the wind, it could shed a little light on why predators can discern sounds even in heavy winds.
According to research (see the June ’09 issue of PX magazine for the reference), a coyote has a maximum hearing range of 67-44,000Hz, with a sweet spot of 100-30,000Hz, and a max sensitivity at 8,000Hz. (For comparison, a fox has a range of 50-28,000Hz, with a sweet spot of 100-6,000Hz, and a max sensitivity of 1,000Hz.) The average human covers 30-17,600Hz with a max sensitivity of 4,000Hz. The sound frequency of wind exhibits higher SPL in the lower frequencies (15-100Hz) and drops roughly 10dB every 450Hz (rough approximation over the 200-2,000Hz range). Because the coyote’s ear cannot pick up frequencies below 67Hz, it can effectively filter roughly 80% of the wind’s maximum SPL range. On the other hand, human ears comparatively only filter roughly 30%. These percentages are not hard values; they were merely estimates of areas under SPL curves. However the idea is qualitatively sound, and this effect may partially explain our difficulty of hearing sounds from e-callers during windy conditions and why coyotes don’t seem to have that problem.
Is my theory unimpunable? Definitely not, but it’s something to think about the next time you blast your e-caller during a windy day.
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Category: Dr Shawley's Blog
