Chandler's plan to install high-frequency Dog Silencers to stop barking in Shawnee Bark Park has hit a snag. The problem: When one dog barks, those nearby also get zapped with an annoying sound.

Some critics say the contraptions - triggered by barking and audible only to canines - were not designed for public places and can harm dogs that aren't barking.

It's the latest controversy in more than a year of conflicts over use of the popular park southwest of Alma School and Elliot roads and the disruption that dogs and their owners bring to the neighborhood. A committee of representatives from both sides couldn't come up with a compromise after months of discussion, Community Services Director Mark Eynatten said. The stalemate and a suggestion by park users to consider technology led to the recent purchase of four Dog Silencer Pros from Medford, Ore.-based Good Life LLC for $360, he said.

But when word of the purchase got out, a few dog owners e-mailed objections to city officials, saying the devices pose health and behavior risks. That prompted Eynatten to delay installation. He said he is now seeking information about the potential effects on dog health.

"The fact that the bark-park users on the committee brought forth this idea with assurances that the devices do not harm dogs gave the recommendation substantial validity," wrote resident Norton Rodgers, a regular dog-park visitor who objected to the installation.

Rodgers believes Dog Silencers are not designed for public places and may disrupt canine behavior and undo years of owner training if they are installed in Shawnee Park. That's because the device's sound, which is irritating to dogs but inaudible to humans, goes off when a dog barks.

Animals that aren't barking also hear it and may think whatever they are doing at the time is something bad, Rodgers said. "One dog barks and they all suffer. What galls me is they went out and bought these things without doing their homework."

Good Life spokesman Sean Moeschl said dogs associate the irritating sound with barking, not other behaviors, and his company has had no feedback from users about negative effects on non-barking dogs. However, in the four years that Good Life has been marketing Dog Silencers, only Chandler's have been purchased for installation in public parks, he said. The only other government buyers have been police departments that purchase the devices to manage neighborhood barking-dog complaints on private property.

Dog Silencers pick up barking up to 75 feet away; the irritating sound activated by barking travels up to 300 feet, Moeschl said.

Although some neighbors around Shawnee Bark Park have complained about odor, traffic and crowds, the predominant gripe to city officials is about barking. Neighbor David Gordon told Parks Board members in November that he hears hours of "dog fights followed by people screaming for their dogs to stop . . . more than a reasonable person should be expected to endure. There is no escape; the dog park is my noisy neighbor."

A proposal during that board meeting to shorten park hours met with protests from users, who said the facility is a popular gathering place that creates human and canine bonds and you can't blame dogs for barking.

As a compromise, the city installed electronic gates that enforce the existing hours: 6 a.m. to 10:30 p.m.