Phonet′ics, the science of the sounds of the human voice. Sound is produced by the expulsion of air from the lungs through the windpipe. When this air in its passage through the throat sets the vocal cords in vibration, voice is produced. After passing through the throat the voice enters the mouth or nose or both. As a practical science, phonetics comprehends not only a knowledge of the sounds uttered in human speech, but the invention or discovery of an alphabetical symbol to represent each. The sounds are of two kinds: Fixed sounds, where the cavities of the mouth remain unchanged during the passage of the air; and glides, where these cavities are constantly changing or, in other words, where the utterance is variously modified by the tongue, palate, lips and teeth. The former sounds are called vowels, and in English are represented by the letters, a, e, i, o, u, y; the latter sounds are called consonants, that is, with-sounders, as they are sounded with the vowels, but not alone. The great variations in spelling and pronouncing English have long been a source of perplexity to foreigners learning our language, and have caused many “phonetic reformers” to arise, with plans for producing uniformity; but none of these has ever been adopted, except in the case of a few words. Perhaps the reason of this is that, however “irregular” may be the spelling of so many words, yet the forms in which they are written have become as firmly fixed in our mental habit as are the sounds they represent and the ideas conveyed by those sounds; hence we can never consent to any changes, except those that are gradual and proceed as by a growth. Another difficulty in the phonetic reform would be that, even if it were possible to devise a fixed alphabetical symbol for every sound or combination of sounds, to which all good writers would conform, the pronunciation of words would at once begin to vary and in time our spelling and pronunciation might be as “irregular” as now.