THE VOICE 601 



We may regard the development of a race of speaking ani- 

 mals as dependent upon a corresponding advance in brain- 

 structure, whether that was acquired by a sudden and pro- 

 nounced variation, or by gradual additions of increase in cer- 

 tain regions of the brain, or whether to the first there was then 

 added the second. 



Apart from speech proper, there is a language of the face 

 and body generally, in which there is much that we share with 

 lower forms, especially lower mammals. Darwin, noticing this 

 resemblance, regarded it as evidence strengthening the belief 

 that man is derived from lower forms. Why should the forms 

 of facial expression associated so generally with certain emotions 

 among different races of men be so similar to each other and 

 to those which the lower animals employ, if there is not some 

 community of origin ? This is Darwin's query, and he con- 

 sidered, as has been stated, that the answer to be given was in 

 harmony with his views of man's origin, as based on an alto- 

 gether different sort of testimony. 



The high functional development of the hand and arm in 

 man, and the use of these parts in writing, are suggestive. 



Sunmiary. — The musical tones of the voice are caused by the 

 vibrations of the vocal bands, owing to the action on them of 

 an expiratory blast of air from the lungs. In order that the 

 bands may act effectively, they must be rendered tense and ap- 

 proximated, which is accomplished by the action of the laryn- 

 geal muscles, especially those attached to the arytenoid carti- 

 lages. We may speak of the respiratory glottis and the vocal- 

 izing glottis, according as we consider the position and move- 

 ments of the vocal bands in respiration or in phonation. 



The pitch of the voice is determined by the length and the 

 tension of the vocal bands, and frequently both shortening and 

 increased tension are combined; perhaps we may say that al- 

 tered (not necessarily increased) tension and length are always 

 combined. 



The quality of the voice depends chiefly upon the supra- 

 laryngeal cavities. 



It is important to remember that in all phonation, in the 

 case of man at least, many parts combine to produce the result; 

 so that voice-production is complex and variable in mechanism 

 beyond what would be inferred from the apparent simplicity of 

 the mechanism involved; while the central nervous processes 

 are, when comparison is made with phonation in lower ani- 



