It’s pretty obvious that dogs have more powerful noses than humans, but how well can they hear? You might have read that dogs have far better hearing than humans, but it’s not quite that simple. In his book, “How Dogs Think,” Stanley Coren, Ph.D, says, “The truth of the matter is that, for some sounds, a dog’s hearing is really hundreds of times better than ours, whereas for other sounds, dogs and humans have sound sensitivities that are very much the same.”
Where dogs really shine is with higher-pitched sounds. The average adult human cannot hear sounds above 20,000 Hertz (Hz), although young children can hear higher. (Hertz is a measure of the frequency of a sound, and the higher the frequency, the higher pitched the sound.) Dogs, on the other hand, can hear sounds as high as 47,000 to 65,000 Hz. These are sounds far too high-pitched for us.
In addition, at high frequencies dogs can detect much softer sounds than we can. The loudness or intensity of a sound is measured in decibels (dB) with 0 dB being the average intensity of a sound that can just barely be heard by a young human. So, sounds too quiet for humans to hear are given a negative decibel rating.
According to Coren, when sounds are between 3,000 and 12,000 Hz in frequency, dogs’ ears are far more sensitive than ours. They can hear those sounds when they are between -5 dB and -15 dB on average. That means dogs can hear sounds that are not loud enough for our ears. For sounds above 12,000 Hz, dogs’ ears have sensitivity so much higher than humans that a comparison would be pointless.
Wired for Prey
It’s thanks to their predatory heritage that dogs can hear high-pitched sounds so well. Wolves, dogs’ ancestors, prey on small rodents such as mice, so the ability to hear the tiny animals’ squeaks is important for survival. Humans, who evolved to cooperate with other humans, have ears that are tuned to the pitch of the human voice.
This sensitivity to higher-pitched sounds likely explains several phenomena involving dogs. Rather than having ESP, dogs may predict earthquakes using their highly sensitive ears. And their ability to predict somebody’s arrival at your door is likely due to their ability to detect the sound of a car before you can hear it, rather than any sixth sense. Finally, dogs can be so distressed by everyday noises, like a vacuum cleaner or power drill, because they sound louder to dogs than to humans. And dogs can hear high-pitched noises from these devices that we can’t detect.
When it comes to the remaining detectable frequency range, dogs and humans can both hear these sounds, and the sensitivity of our ears is about the same. However, human ears have a maximum sensitivity of 2,000 Hz. Not coincidentally, that frequency is right in the middle of the range of human speech. On the other hand, dogs have a maximum sensitivity of 8,000 Hz, much better suited to hearing their prey.
Dogs also have an amazing ability to detect tiny differences between frequencies. Coren explains that they can hear “the difference between the musical note C and another note that differs by one-eighth of the distance between that C note and C sharp.” That puts tone-deaf humans to shame. On the other hand, we can locate sounds better than dogs. Humans can tell the difference between two sounds that differ in location by an angle of only one degree, whereas dogs need eight degrees of separation.
Testing a Dog’s Hearing
Researchers know what humans can hear because they can ask their test subjects, but how do they know what dogs can hear? Early studies involved training dogs to press a lever under a speaker when they heard a sound. Today, a dog’s hearing capabilities can be tested without the dog having to do a thing. The Brainstem Auditory Evoked Response (BAER) hearing test is as simple as placing electrodes on a dog’s head and earphones in his ears. Sounds are played through the earphones, and if the brain shows electrical activity, the dog is considered to have heard the sound. The test doesn’t hurt the dog and only takes a short amount of time.
Just like humans, dogs can lose their hearing with age or from other factors, such as a severe ear infection. The BAER test is a great way to determine the level of hearing loss. Most dogs adapt well when their ears fail, and you can continue to communicate using body language and hand signals. Also, the ability to detect high-pitched sounds is usually the last to go, so louder, high-frequency sounds, like a whistle, may work even when your dog can no longer hear your voice.