A human language is a signalling system. As its materials, it uses vocal sounds. It is important to remember that basically a language is something which is spoken: the written language is secondary and derivative. In the history of eqch individual , speech is learned before writing, and there is a good reason for believing that the same was true in the history of the race. There are primitive communities that have speech without writing, but we know of no human society which has a written without a spoken one. Such things as the sign language of the deaf and dumb people are not exceptions to this rule, even if used y people who cannot speak, and have never been able to speak, these languages are derived from the spoken language of the community around them.
The vocal sounds which provides the materials for a language are produced by the various speech organs. The production of sound requires energy, and this is usually supplied by a diaphragm and the chest muscles, which enables us to send a flow of breadth up from the lungs. Some languages use additonal sources of energy: it is possible to make clicking sounds by muscular movements of the cheeks and lips, and such sound for example are found in some of the languages o Africa. But in English we rely in the outlow of air from the lungs, which is modified in various ways by the ‘set’ of the organs thatit passes through before finally emerging at the mouth or nose.
First the air from the lungs passes through the vocal cords. These are rather like a small pair of lips attached to the walls of the windowpipe, and we are able to adjust these lips to various positions, from fully closed ( when the flow of air is completely blocked) to wide open ( which the flow of air is quite unobstructed). In one of the intermediate positions, the vocal cords virate as the air passes hrough, and produce a musical tone called voice. We can vary the pitch of the voice ( how high or low the tone is on the musical scale), and the pitch of our voices vary constantly as we speak, producing the characteristics melodies of English sentences. Sounds in which voice is used are called voiced sounds, but some speech sounds are made with the vocal cords in the wide open positions, and are thereore voiceless. The presence or absence of voice can be detected by covering the ears with the hands: voiced sounds then produce a loud buzzing noise in the head. If, for example, you cover your ears firmly and utter a long continuous v sound, you will hear voice; if you change it to an f sound, the voice disappears. In fact the English v and f are made in exactly the same way, except that one is voiced and the other voiceless. There are many other similar pairs in English, including z and s, the th of this and the th of thing, and the consonant sound in the middle of pleasure and of washer, which can be called zh and sh. We can play other tricks with our vocal cords: we can sing, or whisper, or speak falsetto: but the two really important positions for speech are the voiced and the voiceless.
After passing through the vocal cords, the stream of air continues upwards and passes out through the mouth, or the nose, or both. The most backward part of the roof of the mouth, called the soft palate or velum, can be moved up and down to close or open the nasal cavity, while the mouth passage can be blocked by the means of the lips or tounge.