THE PRODUCTION OF THE VOICE 325 



gether, the higher the note. The range of the voice depends 

 principally on the degree of tension which the cord can be made 

 to assume. 



Varieties of Vocal Sounds. These are mainly (i) monoto- 

 nous, (2) transitional, (3) musical. 



1. In monotonous sounds the notes have all nearly the same 

 pitch, as in reading. 



2. In transitional sounds there is a gradual change in the 

 tension and approximation of the cords, so that the notes become 

 successively higher or lower, as in the howling of a dog. 



3. In musical sounds the vocal cords have a definite number 

 of vibrations for each successive note a number corresponding 

 to the production of that note in the musical scale. 



The range of the average human voice is from one to three 

 octaves. The highest and lowest notes of females are about one 

 octave higher than the corresponding notes of males. The chief 

 difference between male and female voices is, therefore, one of 

 pitch; but they also differ materially in tone. The difference 

 in pitch is a result of the different length, and therefore the dif- 

 ferent rate of vibration, of the cords in the two sexes. The 

 female cords are about two-thirds the length of the male. 



Before puberty the male larynx resembles the female, but at 

 that period the alae of the thyroid becomes more prominent in 

 the male and the cords increase in length, thus accounting for 

 the change of voice. 



In old age control of the musculature of the larynx is partly 

 lost, the cords become altered and the cartilages ossify. These 

 circumstances make the voice weak and unsteady. 



Speech. Modifications and alterations of the sounds pro- 

 duced in the larynx during and after their production result, 

 under the influence of the sensorium, in articulate speech. These 

 modifications are made chiefly by the tongue, teeth, and lips. 



The speech sounds are divided into vowels and consonants. 

 The distinction is that the vowel sounds are generated in the 



