Margaret Scott, age 10, of Toronto, Ontario, Canada, for her question:
Can a dog really hear better than we do?
For at least 5,000 years, kindly children have been wondering how the animals feel about things. Andy knows this for a fact because he has been listening to their questions for 5,000 years. Or so the old pixie type pooka claims. A few years ago, our brainy scientists got interested in the senses of animals how cats see, how dogs smell and hear. Already they know the answers to some of these kindly questions.
An ordinary dog has just about the best sniffer in town. He can smell everything a lot better than we can and dozens of things that our noses never notice. His ears also are a lot sharper than ours. He can hear all sorts of sounds that our ears were not made to hear. We can hear the same low notes, but he can hear them ten times farther away. A dog also can hear a whole range of high high notes that human ears will never be able to hear.
Sounds are invisible energy that jogs back and forth through air, water and solids. The jogs are vibrations .and each note vibrates a certain number of times per second.
`Most human ears can hear high notes of 20,000 cycles.. Most of us can hear the sounds in a range of almost 10 octaves. But sensitive instruments can register sounds higher than 100,000 frequency cycles. The sounds higher than the range of human ears are called supersonic or ultrasonic frequencies.
These supersonic sounds are all around us but we cannot hear them. But dogs and cats can hear some of them. They hear the same low notes as we do, plus a range of about five octaves higher than our ears can hear. Most dogs hear frequencies of 30,000 with no trouble at all.
Perhaps you use a special dog whistle to call your pet home for his dinner. It seems to make no sound at all because its notes are too high for human ears. But your dog hears it, way down the block. When he learns what it means, he soon shows up at the kitchen door for his rightful reward. Andy's cats also come bouncing home when he calls them with a supersonic whistle.
Tests show that most small dogs tend to hear better than big dogs. A chihuahua and a German shepherd both hear prowling footsteps before we do. But usually the little chihuahua hears them.first, even when dozing. The German shepherd can be trained as a splendid seeing eye. The chihuahua can be a valuable "hearing ear" dog. He hears the softest suspicious sounds outdoors and loves to bark loud and clear to alert his family. However, he must be trained not to sound false alarms. The little rascal really knows the difference between a prowling pussycat and a prowling burgler.
Some animals hear higher frequencies than others. So far as we know, the champion is the little upside down bat. He uses a radar system of high pitched squeaks and echoes to guide his acrobatic flights. His ears can hear frequencies up to 130,000 and perhaps higher. This is much much too high for the hearing ability of even a sharp eared chihuahua.