Page:Popular Science Monthly Volume 3.djvu/643

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MANY animals possess the attribute of voice, but man is the only one among them all capable of modulating voice into speech. This he does by changing the shape of the cavities of the throat, mouth, and nose, by the actions of the muscles which move the walls of those parts, and by the movements of the tongue. The latter organ is commonly credited with the most important share of the work; a distinction to which, as we shall soon see, it is far from being entitled.

The sounds of the vowels, in ordinary speech, are produced by a continuous expiration, the mouth being kept open, and the form of its aperture changing with the utterance of each. Certain consonants may also be pronounced, without interrupting the current of expired air, by alterations in the shape of the throat and mouth: h, for example, is the result of a little extra expiratory force; s, z, sh, and j in some cases, th, l, r, f, and v, may likewise all be produced by continuous currents of air forced through the mouth, the shape of the cavity of which is peculiarly modified by the tongue and lips. All the other consonantal sounds of the English language involve the blocking of the air-current in its passage through the mouth. In the case of m and n, it is prevented from issuing through the lips, and is forced through the nose; while the remaining consonants, termed explosives, such as b and p, are produced by shutting the passage in both mouth and nose, and forcing the vocal current through the obstacle furnished by the mouth, changes in the form of which give to each consonant its peculiarity.

This, in brief, is the explanation given by Huxley, of the formation of articulate sounds; and it will be seen that, while the tongue is intimately concerned in modifying the shape of the oral cavity, only a few of the sounds, such as those of d, t, s, sh, l, and r, and sometimes g, require its presence, and most of these even may be approximately sounded without it. In his "Elementary Lessons in Physiology,", Prof. Huxley relates the case of a man, examined by him, whose tongue had been removed as completely as a skilful surgeon could