554 MUSCLE-NERVE PHYSIOLOGY 



length of the vocal cords in the two sexes; their relative lengths in men and 

 women are as three to two. 



The boy's larynx resembles the female larynx. His vocal cords before 

 puberty are not two- thirds the length of the adult cords; and the angle of the 

 thyroid cartilage is as little prominent as in the female larynx. Boy's voices 

 are alto and soprano, resembling in pitch those of women, but louder, and 

 differing somewhat from them in tone. But, after the larynx has undergone 

 the change produced during the period of development at puberty, the boy's 

 voice becomes bass or tenor. While the change of form is taking place the 

 voice becomes imperfect, frequently hoarse and crowing, and is unfitted for 

 singing until the readjustment of the larynx is complete and the muscles 

 which control the vocal cords are again coordinated. In eunuchs who have 

 been deprived of the testes before puberty, the voice does not undergo this 

 change. The voice of most old people is deficient in tone, unsteady, and 

 more restricted in extent. The first defect is owing to the ossification of the 

 cartilages of the larynx and the altered condition of the vocal cords; the want 

 of steadiness arises from the loss of nervous power and command over the 

 muscles, the result of which is here, as in other parts, a tremulous movement. 

 These two causes combined render the voices of old people void of tone, un- 

 steady, and weak. 



Most persons have the power, if at all capable of singing, of modulating 

 their voices through a double series of notes of different character: namely, 

 the notes of the natural voice, or chest-notes, and the falsetto notes. The 

 natural voice, which alone has been hitherto considered, is fuller, and excites 

 a distinct sensation of much stronger vibration and resonance than the 

 falsetto voice, which has more of a flute-like character. 



The Quality of the Voice. The difference in quality of voices, seen 

 when two or more persons sound the same note, is due to differences in 

 resonance in the cavities of the mouth and larynx and also of the nose. The 

 shape of the roof of the mouth, the regularity of the teeth, and the size of the 

 tongue, and the size and clearness of the nasopharynx are all factors. The 

 size and shape of the larynx and mouth cavity which influence the voice 

 quality can be controlled to some > extent during singing, and this is a special 

 point of training in voice culture. 



Speech. Besides the musical tones formed in the larynx a great number 

 of other sounds can be produced in the vocal tubes, between the glottis 

 and the external apertures of the air-passages, the combination of which 

 sounds into different groups to designate objects, properties, actions, etc., 

 constitutes language. The languages do not employ all the sounds which 

 can be produced in this manner, the combination between certain sounds 

 being often difficult. Those sounds which are easy of combination enter, for 

 the most part, into the formation of the greater number of languages. Each 

 language contains a certain number of such sounds, but in no one are all 



