STORRS, Conn. – Deer whistles placed on car bumpers to scare the animals away make noises that the deer can’t hear, according to a new study by the University of Connecticut.

Peter Scheifele, an animal bioacoustics and audiology researcher, studied the plastic devices and found that the frequencies they produce are not within the hearing range of deer.

The whistles are marketed as safety devices that make deer stand still, with the aim of keeping deer from running into the road and getting hit by cars.

The devices are common in Maine – they are sold at auto parts stores and other outlets – and have been used on sheriff’s deputies’ vehicles and Maine State Police cruisers.

Scheifele, who works in the university’s department of animal science, tested six whistles by attaching them to a car and driving between 30 and 40 mph. He said the whistles typically made a signal at frequencies of 3 kilohertz or 12 kilohertz.

Scheifele said the 12 kilohertz sound fell outside the hearing range of a white-tailed deer, which is between 2 and 6 kilohertz.

The lower sound, 3 kilohertz, is too close to the frequency of traffic and becomes buried by the noise from the car, he said.

“All in all, the air whistles do not make sense to me acoustically,” Scheifele said.

Mike Livingston, who works for Living Products manufacturing company in Arvada, Colo., disputed the university’s finding Tuesday. His company makes deer whistles.

“I’ve had them on many vehicles and witnessed deer cocking their heads and looking at the vehicle,” Livingston said. “They seem to work well.”

Livingston said he believes in the product. His company had the whistles tested by an independent company in 1987, and they were found to be 92 percent effective at stopping the deer, he said.

Maine State Police put the whistles on cruisers for more than a decade, but stopped purchasing them last year. State police spokesman Stephen McCausland said there had been no noticeable change since the department stopped using the whistles.

“We stopped using them after reviewing some studies on their effectiveness,” he said.