Phonetics (Gr. , pertaining to sound or speaking), the science of articulate sounds. Articulation depends on the organs of speech, and an adequate knowledge of their functions, and of the laws of sound, has been reached only in recent times through the labors of Briicke, Merkel, Thausing, and Helmholtz. The physiology of language, as far as it treats of the organs of speech and their functions, will be discussed under the title Voice. In this article will be considered only the manner in which the various sounds making up a language are produced, their graphic representation being reserved for the article Weitdstg. Every articulation is founded on an expulsion of breath, and sounds differ according to the number and character of the obstacles encountered by a breath in the course of emission. To utter a vowel, the breath has to pass through a sort of tube formed by the mouth, and a, e, i,,o, and u (pronounced as in Italian ah, ā, ē, ō, oo) are produced by simple changes in the form of this tube, and in the case of a and e also by opening the cavity of the nose. For the French nasal vowels, un, on, in, an, the soft palate is brought down and the air made to vibrate through the cavities connecting the nose and pharynx.

The simplest breathing produces either the spiritus asper (our h) or the spiritus lenis, which the Greeks considered to be inherent in all initial vowels; but the former requires besides the mere emission of the breath a certain position of the soft palate, and the latter a pressure of the glottis. Using the tongue, the hard palate, the teeth, or the lips, to interpose further barriers, these breaths can be modified in eight different ways. By lifting the tongue against the uvula when emitting the breath, we obtain the hard German ch, and with a slight check of the breath the German g; k is produced by contracting the tongue and placing it against the beginning of the hard palate, and if at the same time a hard breath is made to pass through this opening, the sound of the soft German ch is obtained, while the softening of the breath in this position will give the y in the word year. The hard breathing can be modified into an s, the soft into a z, by reaching with the tongue toward the teeth. Sh in ship and si in fusion (=zh) are formed by somewhat hollowing the tongue when drawing it back and allowing its lower surface to rise toward the back of the upper teeth or the palate.

If in emitting the h the tip of the tongue actually touches either the edge or the back of the upper teeth, or is introduced a little way between the teeth, the sound is changed into the English th in three, which can be altered into the soft th in thee by emitting only the soft breathing or spiritus lenis. The lower lip brought against the upper teeth modifies the hard breathing into an f the soft into a v. The German w requires the lips to be brought together when emitting a soft breathing. "When the soft palate or the tip of the tongue is allowed to tremble and to interrupt the stream of air, the intermittent sound of r is produced, which can be rendered more indistinct by raising the tongue and decreasing the vibrations. The sound of I is made by vibrating either one or both lateral edges of the tongue when placed against the upperteeth. The sounds k, t, and p are produced by checking the emission of breath; the first by bringing the root of the tongue against the soft palate, the second by placing the tongue against the teeth, and the third by joining the lips. The English ch is a union of the sounds of t and sh. The difference between p and o, t and d, k and g consists in a narrowing of the glottis for the latter, while for the former it is kept wide open.

For the nasal checks ng, n, m, the breath is emitted through the nose, and at the same time somewhat detained. The hard aspirated checks Teh, th, ph (=k'h, t'h,.p'h, as in uphold with the initial vowel omitted - p'hold), of frequent occurrence in oriental languages, result from gathering the breath and letting it explode audibly as soon as the consonantal contact is withdrawn; and the soft aspirates gh, dh, oh are made by allowing the soft breathing to be heard after removing the consonantal contact. - Max Muller has framed the following scheme of the physiological alphabet:

Max Muller's analysis of several sounds, and hence the grouping of the physiological alphabet, has not been universally accepted. Thus Prof. "W. D. "Whitney contends that his view of the essential difference between vowels and consonants will not bear examination; that his definition of wh as a simple whispered counterpart of w is clearly false; that trilling or vibration is not characteristic of an Z, nor necessarily of an r; that the description of the German ch is both wavering and unintelligible; and that especially his account of the spiritus asper and the spiritus lenis, and his explanation of the difference between such sounds as 2, v, b on the one hand, and s,f, p on the other, is to be rejected. The physical scheme of the English spoken alphabet adopted by Prof. Whitney is the following: