RESPIRATION 263 



arytenoid and transverse arytenoid muscles. The range of 

 an ordinary voice is 2 octaves ; by training 2-| octaves can 

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

 3 J, octaves 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, 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 (Paulsen). 



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

 said, on the tension of the vocal cords, rises and falls some- 

 what with the strength of the expiratory blast ; the highest 

 notes are only reached with a strong expiratory effort. The 

 intensity of all sounds is determined by the strength of the 

 blast, for the amplitude of vibration of the vocal 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, if these terms seem simpler 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 vibration 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 funda- 



