Along with extraordinary vision and an
acute sense of smell, dogs have remarkable powers of hearing. The domestic dog
owes this super-sense to its wild cousins. Have you ever seen a fox
"jumping mice" in the snow?
Its ears swivel and turn as it locates its
prey, even though the little critter is invisible under several feet of the
white stuff. The two ears then hone in like radar on the mouse before the fox
leaps. It arcs several feet through the air and lands on its front paws,
trapping its lunch beneath them.
Domestic dogs have the same ability to
pinpoint tiny sounds at great distances. Before domestication, the dog's
wolf-like ancestors relied on this acute hearing to catch prey and avoid
predation. Now humans train domestic dogs to help people with visual and
Dogs can hear a far wider range of sound
frequencies than humans. Not only do they hear better than humans, but
they also hear more than humans ever can. Have you seen a dog-whistle, often
used in training? It's often called a "silent whistle." It's silent
to humans, but not to dogs!
Dogs experience a soundscape inaccessible to their human companions. On the lower part of the scale, their hearing is much the same. Humans and dogs alike can detect distant thunder rumbling, for example. That would be around 67 Hz. But it's in the higher ranges that dogs excel. At up to 45,000 Hz in the higher range compared to a mere 23,000 Hz for humans, even when they are sleeping dogs can pick up and respond to sounds inaudible to people.
Dogs' sound-response reflex is much faster
than most humans, too. That's because of those independently moving ears. Dogs
can locate, isolate and react to an interesting sound (opening a food tin, for
example!) in 0.06 of a second. That's fast.
Dogs' hearing outstrips humans in terms of
distance and direction by a factor of ten. A sound you might just be able to
hear from 20 yards away would be audible to a dog from a distance of 200 yards.
And those moveable ears allow dogs to pinpoint sounds within that range.
The dog's mobile ears are a wonder in
themselves. It takes 18 specialized muscles to lift, lower, turn, twist, and to
tilt a dog's ears. But these muscles are not only important in motility. They
also contribute to the dog's extraordinary powers of hearing. Deep in the
middle area of the canine ear structure is a network of unique muscle fibers.
These fibers can contract and relax quickly, responding to tiny fluctuations in
vibration. The complex structure of the dog's ear contributes to its ability to
hear such an astonishing range of frequencies.
Humans have many reasons to be grateful to dogs. Their auditory power is one reason. Most dog owners are familiar with seeing their canine friend cock his head, his ears twitching and pivoting, and then a few minutes later a visitor arrive at the door. The same super-sensitive hearing makes dogs such helpful aids to the disabled, and such fine guardians of our homes.