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A MANUAL OF PHYSIOLOGY 



then a (as in path] : then a (as in fane) ; then * : while e is highest 

 of all. A simple illustration of this may be found in the fact that 

 when the vowels are whispered in the order given, the pitch rises. 

 When u or o is sounded, the buccal cavity has the form of a wide- 

 bellied flask, with a short and narrow neck for u, a still shorter but 

 wider neck for o. For e the tongue is raised and almost in contact 

 with the palate, and the cavity of the mouth is shaped like a flask 

 with a long narrow neck and a very short belly. For i the shape is 

 similar, but the neck is not so narrow. For a (as in path) the vowel- 

 cavity is intermediate in form between that of u and e, being roughly 

 funnel-shaped, and the mouth is ratler widely opened. For u (oo) 

 the resonating cavity is made as long as possible, the larynx being 

 depressed and the lips protruded ; for e the resonating cavity is at its 

 shortest, the larynx being raised as much as possible and the lips 

 retracted (Figs. 124 to 126). 



According to Helmholtz, all that the resonating cavity does is to 

 strengthen certain of the partials or overtones of the lary'ngeal note. 

 If this is true, the partials which give a vowel-sound the timbre by 



ou 



FIG. 124. 



FIG. 125. 



FIG. 126. 



which we recognise it as different from other vowel-sounds cannot 

 preserve the same numerical relation to the fundamental tone when 

 the pitch of the latter is altered. Suppose, for example, that a 

 given vowel is sounded with a pitch corresponding to 100 vibra- 

 tions a second, and that the partial which is particularly strengthened 

 by the resonance of the mouth cavity is the fifth overtone, corre- 

 sponding to 600 vibrations. Then when the same vowel is sounded 

 with a pitch of 200 vibrations the reinforced partial which will now 

 give the quality to the sound will still correspond to 600 vibrations 

 a second, since this is the rate which most easily elicits the resonance, 

 but it will not now be the fifth but the second overtone. 



Universally accepted tor a time, the Helmholtz theory has been in 

 recent years assailed, especially by Hermann, who bases his criticism 

 on microscopic examination of curves obtained by the Edison phono- 

 graph, and on reproductions of such records obtained by photo- 

 graphing on a moving drum covered with sensitive paper a beam 

 of light reflected from a small mirror attached to a system of levers 

 whose movements fellow the curves faithfully and greatly magnify 

 them. Hermann has come to the conclusion that the mouth does 



