Q How can dogs hear a dog whistle but people cannot?
— Yue Xi, Shorewood Hills, Wis.
A Dr. Sandra Sawchuk, primary care veterinarian in the University of Wisconsin-Madison School of Veterinary Medicine:
Humans can hear sounds in a range from about 20 to 23 kilohertz at the upper range of their hearing ability. The hearing range of dogs is almost double that.
The dog whistle, which sounds silent to us, produces sounds in the 50-kilohertz range that dogs can hear.
Dogs have better hearing than humans because they can hear these high-frequency sounds and they can hear sounds from farther away. This is because of the way their ears are designed. Their ears are made to cup and move sound in, similar to the way humans can put a hand up to their ear to hear better. Dogs can also move their ears around to hone in on sounds in different directions.
Dogs can hear these high-pitched sounds primarily because of the way they evolved. Wild dogs hunted for a living, and their main prey were little rodents that make very high-pitched sounds. Back before our domestic dogs evolved, they would hear sounds that were high-pitched in order to hunt better.
Some modern dogs, like terriers, have maintained the ability to hear some of those really high-pitched sounds. That’s why terriers are so good at hunting rodents.
Just like people, as dogs get older they can lose their ability to hear.