PHYSIOLOGICAL ANATOMY OF THE YOCAL ORGANS. 4:91 



afterward the manner in which the voice is modified so as 

 to admit of the production of articulate sounds. 



The voice in the human subject, presenting, as it does, a 

 variety of characters as regards intensity, pitch, and quality, 

 and susceptible of great modifications by habit and culti- 

 vation, affords a very extended field for physiological study. 

 Of late years this has been the subject of careful investiga- 

 tion by the most eminent physicists and physiologists ; but 

 to follow it out to its extreme limits requires a knowledge 

 of the physics of sound and the theory of music, a full con- 

 sideration of which would be inconsistent with the scope 

 and objects of this work. AVe shall content ourselves, there- 

 fore, with a sketch of the physiological anatomy of the parts 

 concerned in the formation of the voice, and the mechanism 

 by which sounds are produced in the larynx, without treat- 

 ing fully of their varied modifications in quality. It will 

 not be necessary to treat of the different theories of the voice 

 that have been presented from time to time, except in so far 

 as they have been confirmed by more recent and complete 

 observations, particularly those in which the vocal organs 

 have been studied in action by means of the laryngoscope. 



Sketch of the Physiological Anatomy of the Vocal Organs. 



The principal organ concerned in the production of the 

 voice is the larynx. The accessory organs are the lungs, 

 trachea, and expiratory muscles, and the mouth and reso- 

 nant cavities about the face. The lungs furnish the air by 

 which the vocal chords are thrown into vibration, and the 

 mechanism of this action is only a modification of the pro- 

 cess of expiration. By the action of the expiratory muscles 

 the intensity of vocal sounds is regulated. The trachea not 

 only conducts the air to the larynx, but, by certain varia- 

 tions in its length and calibre, may assist in modifying the 

 pitch of the voice. Most of the variations in the tone and 

 quality, however, are effected by the action of the larynx 

 itself and the parts situated above it. 



