VOICE AND SPEECH. 641 



(moor). When the mouth and throat chambers are so ar- 

 ranged that the air in them has a vibratory rate in unison 

 with any partial in the laryngeal tone, it will be set in sym- 

 pathetic vibration, that partial will be strengthened, and the 

 vowel characterized by it uttered. As the mouth alters its 

 form, although the same note be still sung, the vowel changes. 

 In the above series (a, 6, 06) the tongue is depressed and the 

 cavity forms one chamber; for a this has a wide mouth open- 

 ing; for 6 it is narrowed; for 56 still more narrowed, and the 

 lips protruded so as to increase the length of the resonance 

 chamber. The partial tones reinforced in each case are, ac- 

 cording to Helmholtz 



In other cases the mouth and throat cavity is partially sub- 

 divided, by elevating the tongue, into a wide posterior and a 

 narrow anterior part, each of which has its own note; and 

 the vowels thus produced owe their character to two rein- 

 forced partials. This is the case with the series a (man), e 

 (there), and i (machine), the tones reinforced by resonance 

 in the mouth being 



The usual I of English, as in spire, is not a true simple 

 vowel but a diphthong, consisting of a (pad) followed by e 

 (feet), as may be observed by trying to sing a sustained note 

 to the sound T; it will then be seen that it begins as a and 

 ends as ee. A simple vowel can be maintained pure as long 

 as the breath holds out. 



In uttering true vowel sounds the soft palate is raised so 

 as to cut off the air in the nose, which, thus, does not take 

 part in the sympathetic resonance. For some other sounds 

 (the semi-vowels or resonants) the initial step is, as in the 

 case of the true vowels, the production of a laryngeal tone; 



