Deer whistles? We're supposed to have this argument in the fall. OK, I read the link. I am intrested in this subject. So, according to the study, the deer can hear the closed whistle at 3khz but the open whistle at 12khz is too high for them to hear? Whatever. Here's my study, my butt dyno test if you will. This has to be long winded to get the point across, so bear with me and I'll try to condense. I lived in Ortonville and worked midnights in Romeo. About 30 miles of mixed farm land. Coming home nightly at about 2:30am through deer strike alley. I routinely saw every type of nocternal critter out there. Deer, coon, skunk, rabbit, possum, owls, frogs....One night, BAM! Dumb deer runs into my driver side door. Hard. So, I put deer whistles on my car. Over the next week or two I noticed that I was seeing alot less critters of all types. Especially the small ones. Life went on and I forgot about it. After a year or two the whistles fell off or got blown off in the car wash, whatever, I didn't think much about it. But, the incidences of critter sighting of all types increased. Hit a small critter once in a while and then...BAM! Dumb deer runs into my right front fender. Hard. Then I said to myself, self, maybe you should replace those deer whistles. So I did. And the circumstances repeated themselves. I realized an immediate reduction in critter sightings of all types. Not to say I never see them, cause I do. Just not as often. This all happened back in the mid 90's. I have kept deer whistles on all my vehicles ever since. I still live and commute daily in deer strike alley. I have not hit a deer since, and have hit maybe only two small critters. Coincidence? maybe. Do they work? Dunno. I'll choose my words cautiously and say that they do have an effect. For $ 10 bucks, I'm willing to continue to gamble with them. I've pissed away dumber money than that. I just consider them a good luck charm. One thing I can say for sure and that is they are at least 10% more effective than road bells!