3io VOICE AND SPEECH 



lateral crico-arytenoid and transverse arytenoid muscles. The 

 range of an ordinary voice is 2 octaves; by training z\ octaves can 

 be reached; but in exceptional cases a range of 3, and even 3^, 

 octaves (as in the celebrated singer Catalini) has been known. 



The development of the voice in children is of great interest. At 

 the age of six years the boy's voice has a rather narrower range than 

 the girl's in both directions. The boy's voice reaches its full height 

 in the twelfth and its full depth in the thirteenth year, when the range 

 is almost 3 octaves, its upper limit being a semitone higher than the 

 girl's, but its lower limit a whole tone deeper. When the voice ' breaks ' 

 in boys at the age of puberty it falls about an octave. The control of 

 the vocal organs becomes so incomplete that only in one-fourth of the 

 cases can notes of sufficient steadiness to be used in music be produced. 

 The vocal cords, as may be seen with the laryngoscope, are frequently, 

 though not always, congested. 



The pitch of a note, while it depends chiefly, as has been said, on 

 the tension of the vocal cords, rises and falls somewhat with the 

 strength of the expiratory blast ; the highest notes are only reached 

 with a strong expiratory effort. The intensity of all vocal sounds 

 is determined by the strength of the blast, for the amplitude of 

 vibration of the cords is proportional to this. Besides pitch and 

 intensity, the ear can still distinguish the quality or timbre of sounds ; 

 and the explanation is as follows: Two simple tones of the same 

 pitch and intensity, that is, the sounds caused by two series of air- 

 waves of the same period and amplitude of the same frequency 

 and height, to use less technical terms would appear absolutely 

 identical to the sense of hearing; just as the aerial disturbances on 

 which they depend would be absolutely alike to any physical test 

 that could be applied. But no musical instrument ever produces 

 sound-waves of one definite period, and one only; and the same is 

 true of the voice. When a stretched string is displaced in any way 

 from its position of rest, it is set into vibration; and not only does 

 the string vibrate as a whole, but portions of it vibrate independently 

 and give out separate tones. The tone corresponding to the vibra- 

 tion period of the whole string is the lowest of all. It is also the 

 loudest, for it is more difficult to set up quick than slow vibrations. 

 The ear therefore picks it out from all the rest ; and the pitch of the 

 compound note is taken to be the pitch of this, its fundamental 

 tone. The others are called partial or overtones, or harmonics of 

 the fundamental tone, their vibration frequency being twice, three 

 times, four times, etc., that of the latter. Now, the fundamental 

 tone of a compound note or clang produced by two musical instru- 

 ments may be the same, while the number, period, and intensity 

 of the harmonics are different ; and this difference the ear recognizes 

 as a difference of timbre or quality. The timbre of the voice de- 

 pends for the most part on partial tones produced or intensified in 

 the upper resonance chambers. 



