152 PHYSIOLOGY CHAP. 



decreased depth and breadth of the vibrating portion but to the 

 subdivision of the vocal cords into two vibrating sections, by a 

 nodal line which runs parallel with their edges. When the 

 musculus vocalis is tense and contracted like the edge of the cord 

 in which it is embedded, it vibrates with them, and this prevents 

 the formation of nodal points, and the chest voice consequently 

 results. 



The change from the chest register to falsetto is on this new 

 theory due principally to the relaxation of the musculus vocalis. 

 This change is usually easier and less apparent in women than in 

 men. 



The singer's art is largely directed to equalising the resonance 

 and timbre of the voice in different notes of the scale, so as to pass 

 smoothly from one register to another. Many important exercises, 

 again, aim at facility in altering the strength of a tone without 

 changing its pitch i.e. at singing crescendo and decrescendo. The 

 strength of the laryngeal notes depends on the amplitude of the 

 vibrations of the vocal cords, due in its turn to the pressure of the 

 expiratory current. But when the position of the glottis and the 

 tension of the vocal cords remain unchanged it is possible by 

 increasing the pressure of the air-blast to raise the height of a 

 tone a fifth ; consequently, to produce a crescendo on the same note 

 there must be a compensatory alteration of the vocal cords in order 

 to preserve the same number of vibrations. Compensation in the 

 opposite direction is necessary to produce a decrescendo. These 

 compensations are obtained by decrease or increase of the tension 

 in the vocal cords (relaxation or contraction of the crico-thyroid 

 muscles), or by increase or decrease in the mass of the vibrating 

 parts (contraction or relaxation of the musculus vocalis). Laryngo- 

 scopical observation confirms sometimes the one, sometimes the 

 other interpretation. Both are difficult adjustments, which are 

 easily executed even by experienced singers, and are only learned 

 by long practice. 



" Expression " depends on these modulations of the strength of 

 a note without altering its pitch. No musical instrument is better 

 adapted than the larynx to give expression in singing, for the 

 larynx is a living instrument, brought into direct relation with the 

 emotional and motor centres of the performer by means of its 

 sensory and motor nerves. 



VI. The power of utilising the larynx as a musical instrument 

 is not common as a natural endowment, not only because few people 

 possess the range, volume, and quality of voice that is indispensable 

 for singing, but also because many people do not understand the 

 right use of the larynx as a musical organ, though every one is more 

 or less capable of using it as an organ of speech. 



In former days, particularly towards the end of the eighteenth 

 century, the difference between the singing voice and the speaking 



