Many people who watch snake charmers play music to their cobras often marvel at the way the snakes seem to respond to the music. But research shows that snakes cannot hear high-pitched sounds. If a cobra is blindfolded, you can play music for hours and the snake will sit still. If you remove the blindfold and wave your arms, the snake will raise its head and spread its hood. Therefore, the cobra does not respond to the music, but to the movements of the snake charmer.

To find out how animals communicate, we must observe them carefully; we must carefully monitor the signals passed from one animal to another, as well as study their responses. Scientists and biologists have studied the ways in which animals communicate by observing animals in their natural environments, as well as in zoos, aquariums and laboratories. They have also had to travel to jungles or mountaintops to follow and document the movements and responses of the animals they observe. Other electronic instruments can turn these sounds into pictures on paper, called sound spectrograms, which can be more accurately examined and compared. Scientists also need to bring binoculars, cameras, recorders and other hardware to keep track of all the howls, cries, songs, grunts and barks of the animal world. As you can see, human hearing plays a very little part in the study of animal communication.

Observations and experiments have shown that all animals have a certain "language". It is not a language like ours, for animals do not communicate with words or sentences. But they do have many signals-- they employ body movement and a number of sounds to produce a response in another animal perceiving it. The signals play an important part in the social life of these animals. Most of these signals have to do with parent-young relationships, food hunting, avoiding enemies, meeting of the sexes and keeping in touch with other members of a group.

Vocal signals are constantly exchanged between many mother animals and their young. The hen calls for her chicks with different signals that can mean either food, sleep, or an emergency. Young chicks are also able to give distress calls that alert their mothers. This call is also important when the young birds leave the nest. It makes it possible for their parents to find them if they are accidentally hidden from sight and get lost. There is also a constant calling back and forth between baby and mother among deer, cows, sheep and goats.

Calls of alarm or distress, as well as a special kind of movement associated with it, are common in the animal kingdom. Many birds avoid enemies this way. Gulls are often pests on the landing strips of airfields, so playing fake alarm calls is a way of getting rid of them. Many kinds of deer have hisses or barks that warn the herd of danger. Alarm calls by baby monkeys and apes immediately bring their parents to their side. Warning calls by prairie dogs are signals for these animals to dash into their holes.

Animals also use their voices to produce food calls. The call brings many of the same species and from all directions, like what seagulls do when they spot a huge school of fish. Animal that hunt other animals have special hunting cries. The gray wolf calls the pack with a long smooth howl when it finds food. While the hunt is on, short rapid barks keep them together. When the prey is being pulled down, the wolves howl and snarl like a bunch of dogs.

All animals have ways of attracting members of the opposite sex with they are ready to mate. Sometimes males make thumping sounds and turn into different colors so they can provide a sound and a sight signal to the females. Some female snakes attract males by their movements and their odor. Odor is also a powerful signal used by voiceless mammals. Often there are special glands in their skin that give off powerful scents. These are then deposited on trees or rocks for prospective mates to follow.