THE RANGE OF THE VOICE. 1207 



also, by variations in the strength of the current of air, and not at 

 all, or only in the slightest degree, by changes in the size or shape of 

 the adjacent cavities. 



Tone intensity. — The intensity or loudness of tone will be deter- 

 mined by the amplitude of the vibrations of the margins of the 

 membranes (vocal cords), and its pitch will be influenced by arrange- 

 ments which cause an increase or decrease of the tension of the margins 

 of the membranes. The pitch may also be raised by increasing the 

 force of the blast of the air, since this will also increase the mean tension 

 of the margins of the elastic membranes. 



With tones of medium pitch, the pressure in the trachea has been 

 found to be about 160 mm. of water ; with tones of high pitch, 920 mm. ; 

 and with tones of very high pitch, 945 mm. ; while in whispering it may 

 fall to a pressure of only 30 mm. 



Tone pitch. — Pitch, so far as the vocal cords are concerned, depends 

 on the number of vibrations per second, or, to put it in another way, on 

 the length of time occupied by each vibration. This again will be 

 determined by the length, thickness, elasticity, and degree of tension of 

 the cords, and on the strength of the blast of air. Other conditions 

 remaining constant, the greater the length of the cords the lower will be 

 the pitch. 



The range of the voice. — The range of the human voice is about 

 three octaves, from/a^ (87 vibs. per second) to sol t (768 vibs.). In men 

 the vocal cords are more elongated than in women, in the ratio of 3 : 2, so 

 that the male voice is of lower pitch, and is usually stronger. At the 

 age of puberty, the larynx grows rapidly, and the voice of the boy 

 " breaks " in consequence of the lengthening of the cords, generally 

 falling an octave. A similar change, but less in amount, occurs at 

 the same period in the female. At puberty in the female there is an 

 increase of about one-third in the length of the glottis, but it is nearly 

 doubled in the male. 



Some of these changes have been carefully studied by Paulsen. 1 In girls, 

 in the sixth year, the pitch ranges from a to /"#. From this period there is a 

 slow increase of range in the lower voice tones, while a more rapid extension 

 occurs in the range of the upper tones. The lowest limit of pitch occurs about 

 the age of 12 in the girl's voice, and the highest is reached in the eleventh 

 year. In the boy's voice the range about the age of 6 years is more limited, 

 lying between b and /". At first the upper range is extended rapidly, 

 reaching the highest point about the twelfth year, and the lower range 

 increases more rapidly than in girls, reaching the lowest pitch in the 

 thirteenth year. The shrieking voice of a child may, according to Stevens, 2 

 rise as high as g'" (3072 v. s. per second), and sometimes screams may even 

 reach from 5000 to 6000 v. s. per second (v. s. = single vibrations). 



In advanced life the upper tones gradually weaken, and ultimately dis- 

 appear, while the character of the voice also changes, owing to loss of 

 elasticity caused by calcification (or ossification), which first begins about 

 middle life in the thyroid cartilage, then appears in the cricoid, and much 

 later in the arytenoids. Eunuchs, as a rule, retain the voice of childhood ; 

 and by careful training in normal persons it is sometimes possible to so 

 modify the development of the larynx that an adult male can still sing the 

 soprano parts used in cathedral choirs. 



The ranges of the different varieties of the human voice arc shown in the 



1 Arch. f. d. ges. Physiol., Bonn, Bd. lxi. S. 407. 

 " Phys. Xev.,T$.Y., 1895, vol. iii. p. 230. 



