158 PHYSIOLOGY CHAP. 



The fact that the vowel limits are reached when the resonating 

 cavity is most restricted, and blocks the passage of the air, agrees 

 with the fact that it is impossible to sing u and i very long and 

 loud like the other vowels. According to Wolf u can only be 

 heard distinctly at 280 paces, i at 300, while a is quite audible 360 

 paces distant. 



On the other hand the vibrations of the walls of the resonance 

 cavity produced by the vibration of the air is maximal with the 

 vowels u and i, minimal with a. On stopping the ears, u and i 

 sound very loud to the ear, a much less so. On applying the palm 

 of the hand to the head, the cranial bones are felt to be vibrating 

 at u, still more strongly at i, and not at all at a, e, o. This fact has 

 been utilised in teaching deaf mutes to pronounce i, which they find 

 the most difficult. 



The diphthongs should not be confused with the intermediate 

 vowels. Gruumach erroneously regards a, ii, o as diphthongs ; in 

 our opinion it is more correct to define them with Goidanich, as 

 organic alterations of the normal vowels. All the intermediates 

 represent special vowel sounds due to special positions of the phona- 

 tory apparatus. In diphthongs, on the contrary, as Briicke noted, 

 there is a rapid passage from the position of one vowel to that of 

 the next, the first being almost always accentuated. In the 

 diphthongs au ( = how), ai ( = high), etc., the first vowel functions 

 as the sonant, the second as a consonant. 



VIII. The formation of the different vowels is thus funda- 

 mentally due to the special positions assumed by the pharyngo- 

 buccal cavity acting as a resonator, and we next have to determine 

 the physical nature of the vowels, i.e. the partial tones of which 

 they are composed, and the relations of intensity on which their 

 timbre or quality depends. This problem is more complicated 

 than appears at first sight. 



Generally speaking, the sound of any musical instrument is 

 a compound, in which one fundamental tone, the deepest and 

 strongest, and several harmonic over-tones, weaker in proportion 

 as their pitch is higher, can be distinguished. But this theory is 

 not applicable to the human voice, especially not to the complex 

 sounds in which we can distinguish the specific characters of the 

 different vowels. This is evident from the following facts : 



(a) The different vowels can be recognised even when they are 

 whispered, that is, uttered without any laryngeal voice. 



(b) The different vowels can be uttered either in speaking or 

 singing to the same musical note. 



(c) Any vowel may be sung to different notes of the scale, and 

 recognised for each note. 



These three points suggest that the complicated laryngeal 

 sounds acquire their special vowel character from the pharyngo- 

 buccal cavity, which acts as a resonator, and reinforces certain 



