Page:Popular Science Monthly Volume 9.djvu/418

394 current from the lungs or from any other source. That this is the case is shown by certain decisive and very interesting experiments. On opening the mouth and adjusting the lips for the pronunciation of a given vowel (though without uttering the slightest sound), the vowel may be rendered sonorous by placing in front of the mouth a vibrating tuning-fork. This method was first applied by Helmholtz. The same result may be obtained by bringing in front of the open mouth, through a tube with narrow terminal orifice, a current of air from a pair of bellows. This plan originated with M. König. Thus it is seen that the various sounds known as vowels depend simply on the form of the resonating cavities, the pharynx and the mouth. When these cavities alone are in action, the voice is aphonic, whispering; it is sonorous when the vocal cords vibrate. For a long time it was held by physiologists that vowels pronounced even in a whisper come from the glottis; precise information concerning these phenomena is of very recent date.

The number of vowels is generally restricted to five, six, or seven; these may be regarded as natural types, being found in nearly all languages. But, in addition to them, there are intermediate vowels, and a multitude of vowel combinations, so great is the power of modification possessed by the buccal cavity. Then there are nasal intonations (very abundant in the French language) produced by depressing the velum palati. A language might consist only of vowels, says Max Müller, and indeed this is very nearly the case with some of the Polynesian dialects.

Most languages possess aspirates of more or less harshness. In French they are very few and weak, but in German they are frequent and strong, while in Arabic they are specially forcible. Aspiration requires the action of the glottis; the orifice is reduced for an instant, and the air, arrested by this obstacle, in issuing through the narrow slit, produces a sound of something brushing against the vocal cords. The aspirate is sometimes sonorous in the Semitic languages. The guttural sounds of the Arabs used to be the subject of grave discussions among linguists, but Czermak put an end to these controversies. That learned physiologist, having fallen in with an Arab, availed himself of the opportunity to examine with the laryngoscope an organ capable of producing a sonorous aspirate. The whole matter was now plain: it was found that, while the epiglottis was depressed, the vocal cords were in close contact; the orifice being thus absolutely closed, the current of air driven against the roof produces a vibration beneath the glottis, in the fissure of the larynx.

The sounds produced in the buccal cavity are broken up on