154 PHYSIOLOGY CHAP. 



The ability to sing depends not on the construction of the 

 larynx, but on the possession of the proper nervous mechanism, by 

 which both the auditory sensations and the tactile and muscular 

 sensations are capable of guiding the volitional impulses in such a 

 way that these are promptly and accurately transmitted to the 

 corresponding muscles. Congenital defects in these nervous 

 mechanisms can also, to some extent at least, be overcome by long 

 and steady practice, just as a violin player is able in a wonderful 

 way to cultivate the nervous mechanisms which move the muscles 

 of his hands. A perfect singer is not born, but trained, as a 

 concert player is developed after long practice ; but of course in 

 either case a favourable congenital predisposition is indispensable 

 to the mastery of the art. 



It is possible by minute and careful analysis of the voice to 

 detect comparative correctness or faults of its formation, as well as 

 of the different notes of the musical scale which it is able to 

 produce. 



A voice is " true " when the vibration numbers of its notes 

 correspond exactly to their place on the scale ; it is " false " when 

 the vibration numbers are greater or less than those of the notes. 

 Kising (crescenti) voices are the more usual ; falling (calandi) voices 

 less common, except in a singer whose voice is worn out. It is 

 often the case that certain notes are false, while others are in tune. 

 Minor keys are more difficult to sing correctly than major keys. 



Hen sen by Konig's manometric flames, Kliinder by the 

 phonautographic method which records the vibrations of the 

 original tone and the note sung in unison with it, made interest- 

 ing researches on the accuracy of the voice. They discovered that 

 it is very difficult to hold a note with a constant number of 

 vibrations for a given time. Owing to positive or negative 

 variations in the tension of the vocal cords, the truest voices 

 fluctuate in vibration frequency above and below the normal 

 mean. The mean error for any particular note is not more than 

 0'35 per cent ; but in holding on a note, or in singing crescendo 

 or diminuendo it may amount to 1/54 per cent, owing to the 

 difficulty of compensation, even in the larynx of a professional 

 singer with long practice, in forming and holding on the notes. 

 This slight natural imperfection of the voice in keeping on the 

 notes is due not to want of ear, but to the larynx and its ; vocal 

 muscles (thyro-arytenoid muscles), which are incapable no matter 

 how much they are exercised of keeping up the exact, degree of 

 tension required for the several notes of the scale, without slight 

 periodic variations. The slight imperfections in the formation 

 and emission of tones, perceptible even in expert singers, depend 

 more on the ear than on the larynx, and are due to defective 

 sharpness in the memory traces of the respective tones. 



VII. Articulate language is limited to man, and is one of the 



