246 STUDIES IN ADVANCED PHYSIOLOGY. 



increased. If, for instance, the posterior halves of the vocal 

 cords were touching and so not sounding, the sounding 

 portion would be only half as long as before, and our knowl- 

 edge of music would make it evident that the pitch would 

 be just an octave higher. For when a violin string is 

 pressed down at this middle point its pitch is raised by one 

 octave. By varying the length along which the vocal 

 cords are thus pressed against each other, that is, by vary- 

 ing the length of the sounding vocal cord, a corresponding 

 range in pitch is effected. 



4. The range of the humaji voice. The range of the 

 human voice is not far from three octaves, although great 

 singers have frequently exceeded this. On account of the 

 much shorter voice-box in children, the pitch of their 

 voices is much higher. In the case of boys there occurs about 

 the time of puberty a somewhat rapid elongation of the 

 vocal cords, referred to in the common expression, the 

 "breaking of the voice. ' ' This elongation causes a material 

 deepening of the voice, but as the elongation is not the 

 same for all individuals, so there are differences in pitch 

 which we recognize in designating some as bass singers, 

 others as tenor singers. In the case of girls no such elong- 

 ation of the vocal cords seems to take place, and so the 

 pitch of a woman's voice remains about an octave higher 



-Sopran 



-Alt- 



FGABcdefga'bcd e f g a bed e f g a 1} c 

 Bass 



-Tenor- 



Fig. 96. THE ORDINARY RANGE OF VOICE. 



through life. The average range of the human voice for 

 the four usual divisions, bass, tenor, alto and soprano, is 

 indicated in the accompanying diagram. 



