CHAP, vii.] SOME SPECIAL MECHANISMS. 337 



among other and irregular vibrations, the regular vibrations corre- 

 sponding to the several vowels. When we whisper a vowel, 

 we ' set ' the vowel chamber so that it may reinforce the set of 

 vibrations of the particular pitch characteristic of the vowel ; and 

 a well trained ear may recognize in the whispered vowel the 

 dominant tone. 



A vowel then is essentially a musical sound of a special quality, 

 due to the dominance of a particular tone reinforced by the con- 

 formation of the vowel chamber. There are many subsidiary 

 questions connected with the formation of vowels but into these 

 we cannot enter here. We will merely add that in uttering a 

 true diphthong, the conformation of the vowel chamber proper 

 to the initial vowel is changed rapidly but gradually and without 

 any obvious break into that proper to the final vewel. 



918. Consonants. These as we have already said in some 

 cases so far resemble vowels in that they are modifications of 

 the voice, that is to say of laryngeal sounds, caused by the 

 disposition of the parts of the vowel chamber, the disposition 

 however being in all such cases different from that giving rise to 

 a vowel, and moreover the very assumption of the disposition 

 taking part in the generation of the whole sound. Such con^ 

 sonants however are relatively few, the great majority of consonants 

 are caused by changes which set up vibrations in some part or other 

 of the vowel chamber or in the larynx itself ; they are noises 

 which may or may not be accompanied by voice, the vibrations 

 producing a different consonant according as they are or are not 

 accompanied by voice. Such vibrations may be set up in 

 several ways. In the case of many consonants vibrations are set 

 up by the passage being closed and then suddenly opened at a 

 particular part ; such consonants are spoken of as explosives. In 

 the case of these consonants the noise which is their essential 

 part cannot be prolonged, it is momentary in duration, though 

 when it is accompanied by voice the latter may continue for some 

 time. In the case of other consonants the noise is caused by the 

 rush of air through a narrow space and the consonants may be 

 described as ' frictional ' , or the noise may be produced by the 

 vibratory movements of particular parts. Both these kinds of 

 consonants can naturally be prolonged for an indefinite time, and 

 have been called continuous consonants. 



On the other hand the characters of a consonant are also 

 dependent on the particular part of the passage at which they 

 are generated ; and this also may be used as a means of classifi- 

 cation. Some consonants are produced at the lips by the move- 

 ment or position of the lips in reference to each other or to 

 the teeth ; these are called labial and labio-dental consonants. 

 Others again are produced by the movement or position of the 

 tongue in reference to the teeth or to the teeth and hard palate ; 

 these are called dental. Yet others are produced by the movement 



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