The range of human hearing is typically considered to be between 20 Hz and 20 kHz. The top end of a dog's hearing range is about 45 kHz, while a cat's is 64 kHz. It is thought that the wild ancestors of cats and dogs evolved this higher hearing range in order to hear high frequency sounds made by their preferred prey, small rodents. The frequency of most dog whistles is within the range of 23 to 54 kHz, so they are above the range of human hearing, although some are adjustable down into the human range. To human ears, a dog whistle makes a quiet hissing sound. The advantage of the dog whistle is that it doesn't produce the loud disturbing noise that an audible whistle would produce, so it can be used without disturbing nearby people. Some dog whistles have adjustable sliders for active control of the frequency produced. Trainers may use the whistle to simply gather a dog's attention, or to inflict pain for the purpose of behavior modification.