214 HUMAN PHYSIOLOGY 



as in no, and oo as in food, it has the form of a flask with a 

 short neck ; while for the production of a as in ate, and e 

 as in scheme, it has the form of a flask with a long neck. 



Perhaps there are, in the formation of vowels, besides these 

 definite determinants, others which are produced by the 

 resonance of the buccal and pharyngeal cavities, the pitch 

 of which depends upon the pitch of the voice, just as the 

 pitch of an overtone depends upon the fundamental tone. 



Consonants are sounds not accompanied by the voice. 

 They are classified as : 



1. Resonants; m, n, ng\ produced by closing the mouth 

 and driving the air through the nose. 



2. Explosives; b, p, d, t, g, k\ produced by the forma- 

 tion of an obstruction to the expired air, or the removal of 

 such an obstruction (the nasal passage being closed). 



3. Aspirates; zu, f, s, /, s/i, z, zh, th, j, ch\ produced 

 by driving the expired air through a constricted portion of 

 the mouth. 



4. Vibratories; r\ produced by the exhaled air throwing 

 the walls of a constricted portion of the buccal cavity into 

 vibration. 



According to the position of the obstruction or constric- 

 tion in the buccal cavity we can distinguish between labials, 

 dentals, and gutturals. 



The sound of h is formed when the exhaled air is un- 

 obstructedly driven through the mouth while the nasal 

 passage is closed. 



