2IO PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



Application. — In quiet breathing all the muscles 

 are relaxed ; the opening is wide, and the breath comes 

 and goes quietly. In aspiration the condition of the 

 laryngeal muscles is much the same, but the breath is 

 driven more strongly by the respiratory muscles so as 

 to make a rushing noise, but not a vocal sound. In mak- 

 ing a vocal sound the tensors and the closers are brought 

 into action, the cords are made more and more tense and 

 pressed closer and closer together, and the breath is 

 driven through with greater and greater velocity, produ- 

 cing more and more rapid vibration in proportion as the 

 pitch of the voice is higher. The cavities of the mouth 

 and nose above and of the trachea and bronchi below 

 act as resonators to increase the volume and modify the 

 character of the sound. 



2. SONG. 



We have spoken thus far only of the simple voice. 

 Singing is only the skillful modulation of the voice ac- 

 cording to the laws of harmony. This is done by skill- 

 ful use of the vocal muscle in producing a pure sound, 

 and a skillful changing of the play of these muscles so 

 as to modulate the pitch, guided by the ear, and, lastly, a 

 skillful modification of the resonant cavities of the throat, 

 mouth, and nose. We all know the wonderful result. 



The Larynx as a Musical Instrument. — But what kind 

 of instrument is the larynx ? To what shall we compare 

 it ? Some have compared it to a wind instrument, espe- 

 cially a tongued instrument, like an organ pipe, or a 

 clarinet, some to a bird-call. But the favorite com- 

 parison is with the stringed instrument, as is shown by 

 the term vocal cords. But the least reflection is sufficient 

 to show that the comparison is not true. The vocal 

 cords are only about three quarters of an inch long in 

 the male and half an inch in the female. Now, since 



