Police develop command device for canine unit

Police officer Xu Yunlong and his colleagues at a police dog training center in Beijing have been researching the use of high-frequency sounds to give commands to dogs in special situations.

"Dogs can hear high-frequency sounds that humans can't. By using such sounds, police can give the animals orders in situations in which they don't want to be heard, or from long distances," said Xu, a trainer at a police dog training base in suburban Beijing that is home to about 270 dogs.

He and other officers have developed a two-part device that consists of a remote control transmitter, held by a police officer, and an ultrasonic emitter attached to a dog's harness.