Ill 



PROBATION AND AETICULATION 



149 



voice in the sixth year was about an octave, by eleven it was 

 twice as great, by fourteen still more extended. Girls' voices 

 reach their widest range at the thirteenth, boys' voices at the 

 fourteenth year. 



In advanced life the upper tones gradually weaken, and 

 ultimately disappear. A soprano voice nearly always turns into 

 a mezzo-soprano, and a tenor often becomes a baritone. These 

 changes, unlike those of puberty, come on gradually, and are due 

 to loss of elasticity, caused by calcification of the laryngeal 



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a- 



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e^ 

 d- 



cartilages, which begins about middle age, and increases with old 

 age. The thyroid ossifies first ; then the cricoid ; much later the 

 arytenoids. In old age the compass of the voice shrinks, and its 

 resonance diminishes and becomes tremulous, owing to retrogressive 

 changes in the neuro-muscular apparatus of the larynx and the 

 expiratory muscles. 



Voices differ not only in their relative position in the scale, but 

 also in quality or timbre. Just as it is easy to distinguish the tone 

 of a basso concerto from a violoncello, and that of a clarinet from 

 an oboe, so a practised ear can distinguish a bass from a baritone 

 or tenor, and a contralto from a soprano, even when they are 

 singing the same notes. 



Generally speaking, " bright " voices can be distinguished from 



