How Do Dog Whistles Work?

Strolling along London's Zoological Gardens in 1876, Sir Francis Galton stopped in front of the lion enclosure, pulled out a whistle, and began blowing on it. No sound emitted from the device, but the zoo’s occupants seemed to grow agitated.

“It certainly annoyed some of the lions,” he later wrote.

What Galton had was what would become known as the dog whistle, an instrument that works silently to corral and control canines. If you’ve ever seen a dog react to an empty corner of a room or a window with no serial killer lurking outside, you might have assumed you have a very paranoid pet. In fact, the dog was probably reacting to a sound at a frequency not audible to humans—maybe a fire truck wailing in the distance, or an airplane flying overhead.

This superior hearing is the reason dog whistles work. By employing a high-frequency pitch, an owner or trainer can capture a canine’s attention. But there’s a little more nuance to it than that—and a lot more to Galton’s story.

The Origin of the Dog Whistle
How Dog Whistles Work
Using a Dog Whistle

The Origin of the Dog Whistle

Galton was a half-cousin to Charles Darwin and a scientist who pursued a theory of “regression to the mean,” or the idea that humans could only advance for so long before being pulled back to the average. Two musical talents might marry and produce a prodigy, for example, but that prodigy might conceive a kid with little musical ability.

Galton’s theories morphed fairly rapidly into the thoroughly discredited concept of eugenics, or manipulating human reproduction to fit an idealized and race-selected world. (That dog whistle later became a euphemism for thinly-veiled expressions of prejudice makes sense.)

Galton tested his eugenic theories by assessing how different species interacted with the world around them. He grew attached to measuring abilities like hearing in humans and animals, and conceived a device that he hoped would prove differences in desired abilities were inherited rather than due to other factors. The device had a sliding plug that could adjust how much air was being blown inside the tube, including high-frequency notes.

“The base of the inner tube of the whistle is the foremost end of a plug, that admits of being advanced or withdrawn by screwing it out or in; thus the depth of the inner tube of the whistle can be varied at pleasure,” Galton wrote [PDF]. “The more nearly the plug is screwed home, the less is the depth of the whistle and the more shrill does its note become, until a point is reached at which, although the air that proceeds from it vibrates as violently as before, its note ceases to be audible.”

He discovered human ability to hear at higher frequencies declined with age. He also determined cats seemed to have the best hearing, though they didn’t seem to care much about it, and observed smaller dogs were more attuned to the sounds than larger breeds. Clearly, his invention held promise, though his initial objective to use the whistle to further his eugenic theories was not scientifically sound.

How Dog Whistles Work

The whistle would take on purpose beyond Galton’s work. He was, after all, looking to use it across a variety of animals, not just canines. It wasn’t until the 1940s that his idea of a high-frequency whistle began to complement the more traditional, audible dog whistle that had been in use for centuries.

Both dogs and humans can hear at around 20,000 Hz. Dogs, however, can recognize sounds up to 45,000 Hz, a likely result of evolution: Humans needed to hear human voices, while dogs needed to be attuned to sounds from small animals. A “silent” whistle to humans was clearly audible to dogs.

This type of dog whistle was a response to the marketplace: As suburbia was sprawling across the country, there was an opportunity to market whistles that could be used to train dogs in neighborhoods where noise disturbances weren’t welcome. A hunter in a rural setting had little need for a silent whistle; a family living 10 feet from another household might.

The silent whistles had another benefit: Ultrasonic sound that can travel farther. That became useful when a dog was far away from its owner but communication was still necessary. And whether a dog whistle is silent or audible, it’s consistent, whereas a human’s voice might change in pitch or tone and potentially confuse a dog.

Using a Dog Whistle

Dog whistles don’t automatically influence your dog’s behavior. They’re simply a method of cuing a dog, not unlike using hand gestures or speech. The whistle allows a dog to associate the sound with an expected behavior, and that behavior—sit, stay, or eat—needs to be trained.

According to the American Kennel Club, it’s best to introduce a whistle with treats. Blow the whistle, feed your pet something tasty, wait, and repeat. Your dog will quickly come to associate the sound with a reward. Then you can begin combining it with commands. Blow the whistle, tell the dog to sit, and repeat. Eventually, you can just blow the whistle and skip the verbal or gesture command.

Different combinations can be used for different commands. Telling your dog to come back to you might be two toots, a pause, and a toot; fetch might mean three quick bursts. (This is where silent whistles may fall short: It can be hard for a human to know what sound they’re making when they can’t hear it themselves.)

Dog whistles can be used at different frequencies. One way to find the optimal range for your dog is to blow it at a low frequency while your dog is sleeping, then keep going until you find a frequency that causes your pet to awaken.

You’re unlikely to do any harm to a dog with a whistle, provided you don’t blow it too closely to their ears. If your pet seems anxious or agitated by the sounds, you might want to try a different approach.

One thing a whistle won’t do is discourage barking. A dog might be temporarily puzzled or distracted by the sound but it’s likely to get used to it quickly. Blow it too often and the barking might even get worse.

It’s also best to keep use of the whistles restricted to dogs. “I once frightened a pony with one of these whistles,” Galton wrote.

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