232 THE VOICE. 



of an instrument, which is called the laryngoscope, and, 

 simple as it may seem, it is accounted one of the most val- 

 uable of the recently invented appliances of the medical 

 art. 



10. The Production of the Voice. During ordi- 

 nary tranquil breathing no sound is produced in the lar- 

 ynx, true vocal tones being formed only during forcible 

 expiration, when, by an effort of the will, the cords are 

 brought close together, and are stretched so as to be very 

 tense. The space between them is then reduced to a 

 narrow slit, at times not more than -ffa f an ^ nc ^ i n 

 width ; and the column of expired air being forced through 

 it causes the cords to vibrate rapidly, like the strings of a 

 musical instrument. Thus the voice is produced in its 

 many varieties of tone and pitch; its intensity, or loud- 

 ness, depending chiefly upon the power exerted in expell- 

 ing the air from the lungs. When the note is high, the 

 space is diminished both in length and width ; but when it 

 is low, the space is wider and longer (Fig. 57, B, c), and 

 the number of vibrations is fewer within the same period 

 of time. 



FIG. 57. 



THE DIFFLUENT POSITIONS OF THE VOCAL CORDS. 



A, The position during inspiration. B, In the formation of low notes. 

 C, In the formation of high notes. 



11. The personal quality of the voice, or that which en- 

 ables us to recognize a person by his speech, is mainly due 

 to the peculiar shape of the throat, nose, and mouth, and 



10. The formation of true vocal tones ? 



1 1 . To what is the personal quality of the voice mainly due ? What aids are 

 there ? 



