If you don't hear anything when you blow into your dog whistle, don't take it back and ask for a refund -- humans aren't supposed to hear it. Your dog can, though, and it's because of the whistle's unique construction and his hearing, which picks up sounds you never could.
How Dogs Hear
Dogs are able to pick up a wide range of sounds that humans simply cannot. This is because of how sound waves travel. A sound's pitch is measured in hertz -- 1,000 hertz is equal to a kilohertz. The lower the number, the lower the pitch. Humans can detect sounds up to around 23 kHz, but dogs can hear them up to around 45 kHz. This means that when you blow into your high-pitched dog whistle, he can hear it, but your ears just aren't built to do the same.
These whistles are designed specifically so that you can't hear them, which makes them considerably less irritating when used as a training tool. A whistle itself is relatively simple -- when you blow into it, it creates noise by allowing the air to escape through a small opening. The shorter the tube, the higher the pitch, which is why dog whistles are generally so short.
Loud Noise Discomfort
Don't think that the sound of the dog whistle isn't a big deal to your dog just because you can't hear it. Like sitting in the front row at a rock concert, if your dog is close to you and you blow the whistle too hard, it can cause discomfort and pain. Watch for your dog's reaction to the whistle and blow only as hard as you need to in order to get his attention. Blowing it too loudly -- by his standards -- is counterproductive, and may even earn the unwanted attention of other dogs in the vicinity.
The Whistle Advantage
Dog whistles are a popular training tool, and not just because humans don't have to hear them blowing all the time. The whistle has the benefit of sounding the same no matter who is blowing into it, and because dogs learn through consistency, this is highly advantageous. Unlike spoken commands, the whistle makes the same high-pitched noise every single time, so training him to respond to its sound doesn't carry the same margin of error. It is consistent and simple, making it a useful training aid -- even if you can't hear it.
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