656 THE VOICE. [BOOK in. 



teaches that in the chest-voice the vocal cords are somewhat thick, 

 their substance being thrust inward towards the median line by 

 the contraction of the thyro-arytenoidei externi muscles, and the 

 opening between them, sometimes so narrow as to be almost linear, 

 extends along their whole length. In the falsetto voice, on the other 

 hand, the vocal cords are said to be thin and membranous, and the 

 note to be given forth by a vibration, not of the whole width of the 

 cords as in the chest voice, but of the extreme edges only, the lateral 

 parts though not absolutely at rest vibrating with a different rhythm. 

 Though the whole larynx in the falsetto voice is stretched in the 

 antero-posterior direction and the vocal cords correspondingly elon- 

 gated, the rima vocalis does not extend along their whole length ; 

 at their posterior part the cords are in contact, and indeed according 

 to some authors, the high falsetto notes are produced by a sort of 

 'stopping' of the cords. The sense of effort which accompanies 

 the falsetto voice indicates that the changes in the larynx which 

 bring it about, are effected by some special muscular manoauvres, 

 as is also suggested by the fact that the ease with which falsetto 

 notes can be uttered is readily increased by practice. The change 

 from the chest to the falsetto voice is an abrupt one, and the com- 

 bined range may be very extensive, as in the case of persons who 

 can carry on a duet, singing alternately, for instance, in a tenor 

 (chest) and a soprano (falsetto) voice. 



The ventricles of Morgagni are apparently of use in giving the 

 vocal cords sufficient room for their vibrations, and perhaps supply 

 a secretion by which the vocal cords are kept adequately moist. 

 The purpose of the false vocal cords is not exactly known. Some 

 authors think that in the falsetto voice they are brought down into 

 contact with, and thus serve to stop, the true vocal cords. 



At the age of puberty a rapid development of the larynx takes 

 place, leading to a change in the range of the voice. The peculiar 

 harshness of the voice when it is thus 'breaking' seems to be due 

 to a temporary congested and swollen condition of the mucous mem- 

 brane of the vocal cords accompanying the active growth of the 

 whole larynx. The change in the mucous membrane may come on 

 quite suddenly, the voice 'breaking' for instance in the course of a 

 night. 



