THE SPECIAL SENSES 351 



note given by a string may be raised in three ways : tight- 

 ening, shortening, or decreasing the weight of the string. 

 From these facts explain why the voice rises in pitch when 

 we are excited, the muscles at that time being contracted 

 with greater force. Why does a cold with congestion of 

 the cords cause a person to speak in a hoarse, deep voice ? 

 Why does a man, whose larynx is larger than a woman's, 



FIG. 230. FIG. 231. FIG. 232. 



A, Resonance Cavity of the Nose; B, Resonance Cavity of the Mouth; C, Resonance Cavity 

 of the Pharynx; D, Soft Palate; E, Tongue; F, Point at which Vibration begins. 



Fig. 230 shows soft palate (Z>) in normal position, allowing air in naso pharynx to vibrate 

 in unison with initial note. Fig. 231 shows soft palate raised, shutting off this resonance 

 and rendering tone thin and hard. Fig. 232 shows another common fault. The tongue is 

 lowered, increasing the size of the mouth cavity. This increases the volume of the tone but 

 renders the quality harsh and hollow. (Latson.) 



have the deeper voice ? Why does a boy's voice change as 

 his larynx enlarges ? 



A man's voice has usually a pitch of one octave below 

 that of a woman or a boy. The range of the human voice 

 is about two octaves. The voice may also vary in 



634. Volume, or loudness, as well as in pitch. How do 

 we speak loudly at one time and softly at another ? If a tin 

 pan is struck gently, the sound is weak ; if it is struck with 

 force, the sound is louder. We make the voice louder by 

 stronger expiration of the breath, thus sending the air 

 with more strength against the tightened vocal cords. 



