CHAPTER XXI 

 THE LARYNX AND THE EAR 



MAN is a social being. His inclinations are not to live 

 alone, but to be a part of that great human organization 

 known as society. For men to work together, to be mutu- 

 ally helpful one to another, requires the ability to exchange 

 ideas and this in turn requires some means of communica- 

 tion. 1 One meang of communication is found in certain 

 movements of the atmosphere, known as sound waves. 

 In the exchange of ideas by this means there are employed 

 two of the most interesting divisions of the body the 

 larynx and the ear. The first is an instrument for the 

 production of sound waves ; the second is th^. sense organ 

 which enables the sound waves to act as stimuli to the 

 nervous system. 



Nature of Sound Waves. If some sonorous body, as a 

 bell, be struck, it is given a quivering, or vibratory, motion. 

 This is not confined to the bell, but is imparted to the air 

 and other substances with which the bell comes in contact. 

 These take up the movements and pass them to objects 

 more remote, and they in turn give them to others, until a 

 very considerable distance is reached. Such progressive 

 vibrations are known as waves, and, since they act as 

 stimuli to the organs of hearing, they are called sound 

 waves. Sound waves always originate in vibrating bodies? 



1 The problem of social adjustment is but a phase of the general problem of 

 establishing proper relations between the body and its surroundings. 



2 A vibrating body is one having a to-and-fro movement, like that of a clock 

 pendulum or the string of a violin on sounding. Bodies to give out sourtd waves 



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