Q: Do ultrasonic, high-pitch noises repel bears similar to the way the new high-pitch noise makers repel dogs? —Frank V., Somerville, MA; via email
A: Are you saying I'm the same thing as a dog? Why, I'm insulted...even though I do love the delicious, delicious food you give them.
But on to your question: There is some evidence that high-pitched, ultrasonic sounds could repel me in certain cases. I can hear in the ultrasonic range of 16-20 kilohertz, and possibly even higher.
A test conducted with polar bears in the 70s found that ultrasonic frequencies fine-tuned and blasted over large speakers repelled me about 69 percent of the time from a testing perimeter that contained food. Those are pretty decent results, but the scientists who conducted the tests caution that positioning of the speakers, timing, and precise sound amplitude are significant factors. For these reasons, it's unlikely that a ultrasonic dog repeller would work on me.
They were primarily testing ultrasonic bear deterrents for use around permanent sites like oil-drilling stations in the Arctic. The equipment you'd need to lug around is impractical for any hiking or backpacking purpose. Also, testing on grizzly and black bears was limited, though based on biology, the results might be similar. Bear guru Stephen Herrero concedes that an ultrasonic bear repellent is worthy of further study and testing.
Another caveat: Of the testing pool of 74 bears, 51 were strongly repelled, but eight bears exhibited no response, and 15 polar bears actually chose to investigate the source of the sound. So while it might serve as a deterrent, in some cases it can be an attractant, too. Sorry for the confusion—it's just my wildly curious nature.
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