A dog whistle (also known as a silent whistle or Galton's whistle) is a type of whistle that makes a sound in the ultrasonic range. People cannot hear this range, but some animals, including dogs and domestic cats, can catch it. The whistle is used in their training. It was invented in 1876 by Francis Galton and is mentioned in his book in which he describes experiments to test the range of frequencies that can be heard by various animals, such as a domestic cat.
Acoustic characteristics
The upper limit of the range of human hearing is about 20 kilohertz (kHz) for children, dropping to 15-17 kHz for middle-aged adults. The upper limit of the dog’s audibility range is about 45 kHz, and that of the cat is 64 kHz with slight acoustic vibrations. The wild ancestors of cats and dogs are thought to have developed this higher hearing range in order to hear the high-pitched sounds emitted by their preferred prey, small rodents.
The frequency of most dog whistles is in the range of 23 to 54 kHz, so they are above the range of human hearing, although some of them are tuned within the audible range.
Human perception
To the human ear, a whistle is like a soft hissing sound. The advantage of a dog whistle is that it does not make a loud annoying noise for people that could make a normal whistle, so it can be used to train or control animals without disturbing people. Some dog training whistles have adjustable sliders to actively control the frequency generated.
Trainers can use the whistle just to get the dog's attention or to hurt to change behavior.
Different kinds
In addition to light infrasonic whistles, electronic devices for dog whistles that emit ultrasound through piezoelectric emitters have also been invented. Electronic diversity is sometimes paired with circuits to curb the barking of dogs.
History of invention
In the mid-1800s, a dilemma became sir before Francis Galton . He wanted to test his auditory abilities at higher frequencies, but he did not have the equipment to measure them adequately. Using some scientific ingenuity, he set about searching for an object to create sound frequencies that he wanted to study.
As a result, he received a small copper pipe with a slot at the end, in which air will pass through the pipe, emitting an audible signal. Along the pipe, you can move a special item up or down the pipe to create different frequencies. The sliding plug was marked so that accurate recordings could be recorded in the study. This device became known as the Galton whistle.
The book "Requests for the Human Faculty and its Development" in 1883 described some of the pioneering studies that the inventor conducted with a whistle. The scientist and subsequent researchers used these whistles to create increasingly high-frequency tones to test subjects of study, as well as the ability of animals to hear different tones. Galton was able to determine that the normal upper hearing limit of a person is about 18 kHz. He also noted that the ability to hear higher frequencies decreases with age. Reportedly, the author was very pleased to demonstrate this experience on older people.
To his early tests, he adapted a new device to test the hearing of various animals using the sound of ultrasound. He attached the whistle to a long pipe with a rubber ball on the other end. Galton went to the enclosures at the zoo, used a long stick to stretch a whistle to the animal. After a reproduced whistle, he observed the behavior of individuals. He also liked to walk the streets and check which types of dogs could hear higher sounds (small dogs were better at this than large ones). Galton noted that natural selection led to better hearing for cats.
Further development
Early comparative psychologists took crude methods of evaluating animals and refined them. Galton's whistles were used to test hearing in reptiles (Kuroda, 1923), insects (Wever & Bray, 1933), hedgehogs (Chang, 1936), bats (Galambos, 1941) and, of course, rats (Finger, 1941; Smith, 1941 )
Modifications
The Galton whistle was combined in psychological laboratories with acoustic instruments, tuning forks and other hearing aids. The device was made with tables of vibration levels up to five digits. The whistle itself has undergone several design changes to make sounds more accurate. The Edelman Institute, one of the manufacturers of Galton whistles, added a diaphragm to the device to prevent an excessive blow (Ruckmick, 1923). Early psychologists made design changes for the need for their experiments.
At Harvard, Frank Patti invented a blower that could provide a steady, steady stream of air pressure through the whistle for an hour and a half. Despite its simplicity, the whistle was used in very complex and revealing psychological experiments. One of these early experiments combined the Galton whistle and Titchener's sound cell to study differences in ear sensitivity to sound (Ferree & Collins, 1911).
Our days
Since its inception in 1876, the Galton whistle is still in use today. Being an invention of simplicity and imagination, this whistle played an important role in understanding humanity about hearing.
Novel
Galton's Whistle is a science fiction story by the American writer L. Sprague de Camp from the Viagens Interplanetarias series. This is the first (chronologically) set on the planet Vishnu. It was first published as Ultrasonic God in the journal The Future Combined with Fantastic Stories in its July 1951 issue. For the first time, the novel appeared in the form of a book under its current name (preferred author) in the Continent collection.
He also appeared in the collections of "Novelty of Science Fiction" (Belmont Books, 1963), "Good Old Things" (Griffin St. Martin's, 1998). This story has been translated into Portuguese, Dutch and Italian.
Plot of the novel
Surveyor Adrian From, one of a three-man group working in the jungle of the planet Vishnu, was captured by Aboriginal centaur Jelly after his boss was killed and a third member of the team left him. Once at their base, he learns that they are taking orders from Sirat Mongkut, a tyrant previously lost in the area who pretends to be god and has the ambition to unite the tribes beneath him, proclaiming himself as emperor. He uses ultrasonic whistling to strengthen his credibility.
Another captive is Elena Milian, a missionary woman who also went missing. Faced with the choice of joining the kidnapper or his death, Frome pretends to support him, while at the same time trying to find an opportunity to interfere with the grand plan of the madman and escape. When this happens, he kills Sirat and hides with Elena. Successfully saved, he submits to Ganesha, another world in the star system, in order to escape from Elena, because having established a romantic relationship with her, he found that she was an incurable fanatic.
Planet Vishnu is a tropical world that occupies the same star system as Krishna, the main object of de Campa in the Viagens Interplanetarias series.
As written in The Continental Creators and Other Tales of Viagenes and in the 1959 version of de Camp's essay, The History of Krishna, the novel Whistle of Galton takes place in 2117 AD. e.