Thursday, August 18, 2011

Handy-Science evidence, for God's existence about.


  • dog whistle (also known as silent whistle or Galton's whistle) is a type of whistle used in the training of dogs and cats. It was invented byFrancis Galton. This is discussed quite briefly in his book Inquiries into Human Faculty and its Development . In his discussion (Galton 1883:26-27) of his experiments to test the range of frequencies that could be heard by various animals, he notes that cats have the most all-round sensitive hearing, being able from a considerable distance to hear notes too high in frequency for humans to hear, and small dogs can also hear these notes, while large dogs cannot.

The frequency range of a dog whistle is largely out of the range of human hearing. Humans hearing is typically considered to be between 20 Hzand 20 KHz. A dog whistle is within the range of 23 to 54 kHz. Some dog whistles have adjustable sliders for active control of the frequency produced. Depending on the way the whistle is used, a trainer may simply gather a dog's attention or inflict pain for the purpose of behavior modification.
The name dog whistle is often used for both lung-powered whistles as well as electronic devices that emit ultrasonic sound via piezoelectricemitters. The electronic variety are sometimes coupled with bark detection circuits in an effort to curb barking behavior.
These kind of whistles are also used to determine the hearing range of people or for physics demonstrations.


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