526 PHYSIOLOGY 



The characteristic notes were given by Helmholtz as follows : 



O = b 1 

 A= b" 

 E - f, b 1 



cp- ~j --- 1 - - 1 -- ^ - T- 

 !| = 



O 



A 



E 



If the five vowels are whispered loudly, the gradual rise in pitch of the 

 tone is easily perceptible. We do not in this way, however, note the 

 lower component of the sound in the E and I ; this can be brought out by a 

 simple device (Fig. 256). If we place the mouth in the position necessary 

 to produce these different vowels, and then percuss over the cheek, we 

 obtain the typical note for each vowel, the air in the mouth cavity being 

 set into vibration by the percussion. Now shift the finger, which is to be 

 percussed, so that it lies over the pharynx, just behind the angle of the 

 jaw, and percuss again. The note will be observed to rise with U, 0, A, 



A (ah) U(oo) 1 (ee) 



FIG. 256. Shape of the oral cavity in the production of the vowel sounds, A, U, I. 



(GRTJTZNER.) 



and then fall with E. I. With the three vowels U, 0, A, we have a single 

 cavity formed by the lips, the palate, and the tongue ; this cavity is longest 

 and narrowest with U and shortest and most open with A. With E and I 

 the dorsum of the tongue comes up against the front part of the soft palate, 

 so that the mouth cavity is divided into two, the anterior short narrow 

 cavity, and the posterior broader cavity between the soft palate and the 

 base of the tongue. We therefore have two notes produced, one in each 

 cavity. The change in shape of the mouth cavity is shown in the figures. 

 With U and A the cavity seems to be single ; with I the development of 

 a pharyngeal resonating cavity is well shown. Diphthongs are produced 

 by changing the form of the mouth cavity from that of one vowel 

 sound to another, thus AI (the English i) = ah-ee run together and 

 abbreviated. 



Consonants are sounds produced by a sudden check being placed in the 

 course of the expiratory blast of air by closure of some part of the pharynx 



