I shall not subject the reader to the tedium of elaborate details of the system here outlined. This brief exposé of the method of representing the sounds of animals is sufficient to convey an idea of the means by which it is possible to write the sounds of all animals, so that the student of phonetics will recognize at once the character of the sound, even if he cannot reproduce it by natural means.
It may be of interest to describe the character and use of some of the sounds uttered by the chimpanzee. The most frequent sound made by animals is that referring to food, and therefore it may claim the first attention. This word in the language of the chimpanzee begins with the short sound of the vowel “U,” which blends into a strong breathing sound of “H.” The lips are compressed at the sides, and the aperture of the mouth is nearly round. It is not difficult to imitate, and the ape readily understands it even when poorly made. By the method of writing above described it is expressed thus, (I)`.
A sound that is of frequent use among them is that used for calling. The vowel element is “[=U]” long, slightly sharpened. It merges into a distinct vanishing “W.” Expressed in symbols, it is (:)(. The food sound is often repeated two or three times in succession, but the call is rarely repeated, except at long intervals.
One sound which is rather soft and musical is an expression of friendship or amity. It appears to soften in tone and lengthen in duration in a degree commensurate with the intensity of the sentiment. The vowel element is a long “U.” It blends into an aspirated “H.” It is fairly represented by the symbol (:)´.
The most complex sound that I have so far heard made by them is the one elsewhere described as meaning “good.” They often use it in very much the same sense as man uses the expression “thanks,” or “thank you.” It is not probable that they use it as a polite term, yet the same idea is present.
One of the words of warning or alarm contains a vowel element closely resembling the short sound of “E.” It terminates with the breathing sound of “H.” It is used to announce the approach of anything that the animal is familiar with, and not afraid of. If the warning is intended to apprise you of the approach of an enemy, or something strange, the same vowel element is used, but terminates with the aspirate sound of “H” pronounced with energy and distinctness. The vowel element is the same in both words, but they differ in the time required to utter them, and the final breathing and aspirate effects. There is also a difference in the manner of the speaker in the act of delivering the word. It plainly indicates that he knows the use and value of the sounds. At the approach of danger the latter word is often given almost in a whisper, and at long intervals apart, increasing in loudness as the danger approaches. The other word is usually spoken distinctly, and frequently repeated. It is worthy of note that the natives use a similar word in the same manner and for the same purpose.
There are other sounds which are easily identified but difficult to describe, such as that used to signify “cold” or “discomfort”; another for “drink” or “thirst,” another referring to “illness,” and still another which I have reason to believe means “dead” or “death.” There are perhaps a dozen more words that can readily be distinguished, but as yet I have not been able to determine their exact meanings. I have an opinion concerning some of them, but have not yet reached a final conclusion about them.
The chimpanzee makes use of a few signs which may be regarded as auxiliary factors of expression. He makes a negative sign by moving the head from side to side in the same manner as man does, but the gesture is not frequent or pronounced. Another negative sign, which is more common, is a wave-like motion of the hand from the body towards the person or thing addressed. This sign is sometimes made with great emphasis. There is no question as to its meaning. The manner of making this sign is not uniform. Sometimes it is done by an urgent motion of the hand. Bringing it from his opposite side, with the back forward, it is thrust towards the person or thing approaching. The interpretation is, that the ape objects to the approach. The same sign is often made as a refusal of anything offered him. Another way of making this sign is with the arm extended forward, the hand hanging down, and the back towards the person approaching or the thing refused. In addition to these negative signs there is one which may be regarded as affirmative. It is made simply by extending one arm towards the person or thing desired. It sometimes serves the purpose of beckoning. In this act there is no motion of the hand. These signs appear to be innate, and are very similar in character to those used by men to signify the same idea.
It must not be inferred from this small list of words and signs that there is nothing left to learn. So far only the first step, as it were, has been taken in the study of the speech of apes. As we grow more familiar with their sounds, the difficulty of understanding them becomes correspondingly less. I have not been disappointed in what I hoped to learn from these animals. The total number of words that I have been able to distinguish up to this time is about one hundred. Of these I have interpreted about thirty. Of late I have given no attention to the small monkeys. I shall resume the study of them at some future day, as it forms an essential part of the task which I have assumed. The fact that animals are able to interpret human speech is of itself proof that they possess the speech instinct. But a careful study of their habits reveals the further proof that they possess and exercise the faculty of speech. In addition to these facts they sometimes acquire new speech sounds. This is progress. If an ape can take one step in the development of speech, why may he not take two? One instance which is cited in the chapter treating of Moses, my ape companion, I regard as the climax of all my efforts in the study or training of apes, and that is the fact that I succeeded in teaching him one word of human speech. This alone is sufficient to demonstrate that the animal has within him the resources of speech.
In conclusion I again assert that the sounds uttered by these apes have the characteristics of human speech. The speaker is conscious of the meaning of the sound used. The pitch and volume of the voice are regulated to suit the condition under which it is used. The ape knows the value of sound as a medium of conveying thought. These and many other facts show that their sounds are truly speech.