THE LARYNX AND THE EAR 353 



Value of Sound Waves to the Body. From a physio- 

 logical standpoint, the value of sound waves is not easily 

 overestimated. In addition to the use made of them in 

 the communication of ideas, they serve the purpose of 

 protecting the body, and in the sphere of music provide 

 one of the most elevating forms of entertainment. Sounds 

 from different animals, as well as from inanimate objects, 

 may also be the means of supplying needed information. 

 The existence of two kinds of sound instruments in the 

 body the one for the production, the other for the detec- 

 tion, of sound is certainly suggestive of the ability of the 

 body to adjust itself to, and to make use of, its physical en- 

 vironment. Both the larynx and the ear are constructed 

 with special reference to the nature and properties of sound 

 waves. 



THE LARYNX 



The Sound-producing Mechanism of the Body consists of 

 the following parts : 



1. Delicately arranged bodies that are easily set in 

 vibration. 



2. An arrangement for supplying the necessary force 

 for making these bodies vibrate. 



3. Contrivances for modifying the vibrating parts so as 

 to produce changes in pitch and intensity. 



4. Parts that reenforce the vibrations. 



5. Organs by means of which the sounds are converted 

 into the forms of speech. 



The central organ in this complex mechanism is 



The Larynx. The larynx forms a part of the air 



passages, being a short tube at the upper end of the 



trachea. Mucous membrane lines the inside of it and 



muscles cover most of the outer surface. The framework 



