268 A MANUAL OF PHYSIOLOGY 



resonance in the air of the mouth, and so causes its sound 

 to be intensified. The fundamental tone is lowest for u (as 

 in lute). Next comes o; then a (as in path) ; then a (as in 

 fane) ; then i; 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. 



Such is the explanation of the difference of the vowels in quality 

 which was first given by Helmholtz. Universally accepted for a time, 

 it has been in recent years assailed by Hermann, who bases his 

 criticisms (i) on microscopic examination of curves obtained by the 

 Edison phonograph, and (2) on the results of his phono-photographic 

 method. (The record of an Edison phonograph is magnified by a 

 system of levers, the last of which carries a small mirror, on which 

 a beam of light is allowed to strike. The reflected beam falls on a 

 moving drum covered with sensitive paper. Thus the movements of 

 the mirror are greatly exaggerated and photographed.) Hermann 

 has come to the conclusion that the mouth does not act as a mere 

 resonator, but that for each vowel, in addition to the fundamental 

 note due to the vibration of the vocal cords, the pitch of which is, 

 of course, variable, one or, it may be, two other notes, not necessarily 

 harmonics of the laryngeal note, but separated from it by a constant 

 or nearly constant musical interval, are directly produced by the 

 passage of the expiratory blast through the mouth. The fact that it 

 is by no mearts difficult to sing and whistle at the same time shows 

 the possibility of Hermann's view, that a fixed tone can be generated 

 in the mouth by the intermittent stream of air issuing from between 

 the vibrating vocal cords, just as a tone is generated in a pipe by 

 blowing into or over it (Griitzner). McKendrick has also made 

 important investigations on this subject, and has obtained curves by 

 enlarging the phonographic records by mechanical means. 



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 (ff the mouth is shaped like a flask 

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

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

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

 funnel-shaped, and the mouth is rather widely opened. For u (00} 

 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. 96 to 98). 



When the vowels are being uttered, the soft palate closes 

 the entrance to the nasal chambers completely, as may be 

 shown by holding a candle in front of the nose, or trying to 

 inject water through the nares. If the cavities of the nose 



