Question

give reason : A special whistle are used by police trained dog

Answer 1

To human ears, a dog whistle makes only a quiet hissing sound. The advantage of the dog whistle is that it doesn't produce a loud irritating noise for humans that a normal whistle would produce, so it can be used to train or command animals without disturbing nearby people.

Answer 2

A special whistle are used by police trained dog as Herding dogs are also often trainedto respond to whistle commands and dog handlers in the police and military services often use such whistles as an alternative to verbal commands. Surprisingly, a dog that is suffering from hearing loss may still respond to whistle training.