280 PRINCIPLES OF PHYSIOLOGY 



vocalist can produce a trill with the greatest 

 distinctness. 



137. When we listen to musical tones 

 emitted by the human voice we notice varia- 

 tions of pitch, loudness or intensity, and 

 quality. Pitch depends on the number of 

 vibrations executed by the cords in a given 

 time, or, more correctly, on the duration of 

 each vibration. Thus in singing a note, 

 say the middle C of the piano, the cords 

 vibrate about 256 times per second. Each 

 vibration therefore lasts the 1-256 of a 

 second. The greater the number of vibra- 

 tions in a given time the higher the pitch. 

 The range of the human voice is about three 

 octaves from fa|; (87 vibrations per second), 

 to sol fcj (768). 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. 

 At the age of puberty, the larynx grows rapidly 

 and the voice of the boy " breaks " in conse- 

 quence of the lengthening of the cords, and it 

 generally falls about an octave in pitch. The 

 highest pitch reached by the human voice is 

 recorded of Lucrezia Agujari, who was heard 



