As yet we have simple, unarticulated sound; such as when we sing the notes of a tune without words. Speech is made up of articulated voice ; that is, voice modified by the action, not of the lungs, the trachea, or the farynx, but of the throat, palate, teeth, tongue, and lips. Every Variation in tone, however, is pro- duced by a variation in the glottis; and in strength, by the action of the lungs : so that all the parts of this complicated mechanism are continually employed'. Articulation begins when the voice has passed the larynx. The simplest articu late sounds are those which proceed from an open mouth : they are so little modified, that they are called in some other languages by the term voice; and in our own, from a derivative of the same word. In transmitting these, the aper tures of the mouth may be pretty large, or somewhat smaller, or very small ; which produces one set of the variations of vowel sounds :, besides, in passing through the open mouth, the voice may be gently acted upon by the lips, or by the tongue and the palate, or by the tongue and throat : and hence another source of variation ; and thus nine sim ple vowel sounds are produced. When the voice, in its passage through the mouth, is totally intercepted, or strongly compressed, there is 'formed a certain modification of articulate sounds, which is called a consonant. Silence is the ef
fect of a total interception ; and indistinct sound, of a strong compression : hence a consonant is not of itself a distinct ar ticulate voice ; and its influence, in va rying the tones of language, cannot be perceived, unless it be accompanied with an opening of the mouth, that is, by a vowel sound.
' Such is the nature of the mechanism of the human voice ; so complicated, yet so simple : and when we consider the great variety of motions necessary to be per formed by every one who speaks with common fluency, instead of surprize that children are so long before they can arti culate, and express a chain of ideas by words, we shall see ground for admira tion, that this most invaluable acquisition is made so early. The fact appears to be, that the powers of imitation are at that period the principal source of improve ment; and the organs being then more capable of the requisite variation of flex ure than in the later periods of life, sounds are acquired (not indeed without much trouble, And almost incessant exer tion), which at the age of manhood baffle the best:directed exertion.