Yup. first, "you cant prove prevention" so 'studies' really aren't very helpful in practice... same for first hand observation. As well, high pitch sound wont travel far anyway especially forward. But when a deer is right in front of me, if it even gives me 1/10 of a second hesitation from a deer, thats 1/10 of a second I can get to my break... and thats worth 5 bucks.Look up "deer whistles" and you'll find results.
LOTS of controversy about if they even work.
I disagree. Primarily because there seems to be just as little data to conclude ineffectiveness as there is effectiveness. its not a certainty either way. But there is some noise generated by the devices (above 30 mph), thats been tested,interestingly, its a question if deer can even hear that range of sound, that has been tested also.Deer whistles are total quackery.
When deer are spooked they tend to act randomly. The deer seem just as likely to jump into your path as away from your path.
Most deer whistles I've seen are packed with bugs and dirt after just a few hundred miles. At that point they don't make any noise.
If the whistles make you feel more confident, they will help you ride a bit better. But the effect is entirely psychological.