150 PHYSIOLOGY CHAP. 



"dull" voices, while others are "full," i.e. of medium, normal 

 timbre. With bright timbre the larynx is raised, the resonance 

 cavity is short, the mouth wide open, the glottis constricted ; with 

 dull timbre the larynx is lowered, the resonance tube long, the 

 oral opening constricted, the glottis rather wider. The difference 

 in quality is most distinct if the same note is sung with the two 

 vowels A and U. 



It is an important fact that the voice can be varied in the 

 same individual by altering the position of the' vocal organ. 

 When the scale is sung from the lowest to the highest note the 

 voice retains the same quality between certain limits, the pitch 

 only being altered. But in rising gradually to higher notes the 

 voice is not only raised but also changes in quality. The voice is 

 usually divided into three registers, in analogy with the registers 

 of an organ : these are the chest register, the middle register, and 

 the head register, or falsetto. 



Fio. 9f>. Aperture of glottis during emission of low notes (A), and high notes (B), 

 with chest register. 



Laryngoscopical observations show that each register corre- 

 sponds to a particular position of the larynx, which is constant for 

 all notes comprised in that register, the tension of the cords alone 

 being altered according to the height of the notes. In passing 

 from one register to another the position of the larynx changes 

 abruptly. 



The exact positions of the larynx in correspondence with the 

 different vocal registers is a subject of discussion among the 

 laryngologists. 



It is generally admitted that in the chest register the vocal 

 cords vibrate over their whole length ; the aperture of the glottis 

 is elliptical and wide or narrow, according to the pitch of the 

 sounds ; the intercartilaginous portion of the glottis is also more or 

 less widely open ; and, lastly, the vibrations of the cords, which can 

 be clearly seen by the laryngoscope, are transmitted to the chest 

 walls, hence the name of " chest " register (Fig. 99). 



In singing with a head register, or falsetto, the vocal cords are 

 shorter and narrower; the intercartilaginous portion of the glottis 

 is completely closed ; the membranous glottis, on the contrary, is 



