Washington state researchers report discovering what might be the sound of dog laughter. The scientists say the long, loud pant they recorded has a calming or soothing effect on the behavior of other dogs, ABC News reported.

Nancy Hill, director of Spokane County Animal Protection, told ABC she was skeptical when researchers first told her noise would affect the other dogs. "I thought: Laughing dogs? A sound that we're gonna isolate and play in the shelter? I was a real skeptic ... until we played the recording here at the shelter."

ill said when the scientists played the sound of a dog panting over the loudspeaker, the shelter's resident dogs just continued barking. But when they played what they believe is the dog version of laughing, all 15 barking dogs became quiet within about a minute.

"It was a night-and-day difference," Hill said. "It was absolutely phenomenal."

ABC noted although opinions vary whether the dogs are "laughing," one thing is certain: it's a sound that silences other dogs.

Copyright 2005 by United Press International