Dog whistle

It was invented in 1876 by Francis Galton and is mentioned in his book Inquiries into Human Faculty and Its Development,[1] in which he describes experiments to test the range of frequencies that could be heard by various animals, such as a house cat.

To human ears, dog whistles only emit a quiet hissing sound.

Trainers may use the whistle simply to get a dog's attention or to inflict pain for the purpose of behaviour modification.

[3] The electronic variety are sometimes coupled with bark-detection circuits in an effort to curb barking behaviour.

This kind of whistle can also be used to determine the hearing range for people and for physics demonstrations requiring ultrasonic sounds.