OF THE LARYNX,, AND ITS ACTIONS. 933 



these movements takes place during the descent of the voice. A very import- 

 ant adjunct to the production of the higher notes has been pointed out by 

 Miiller, as being afforded by the modification in the space included between the 

 two sides of the thyroid cartilage, which is effected by the thyro-arytenoidei. 

 He had experimentally ascertained that the introduction of a hollow plug into 

 the upper end of the pipe beneath his artificial larynx (and therefore just below 

 the reed), by diminishing its aperture, produced a considerable elevation of the 

 tone. The action may be imitated in the human larynx, when made the sub- 

 ject of experiment, by compressing the thyroid cartilage laterally ; and in this 

 manner, the natural voice could be made to extend through a range that could 

 otherwise be only reached by a falsetto. The influence of the prefixed and super- 

 added tubes, in modifying the tones produced by the Human larynx, has been found 

 by Prof. Miiller not to be at all comparable to that which they exercised over the 

 artificial larynx ; the reason of which difference does not seem very apparent. It 

 appears, however, that there is a certain length of the prefixed tube as there is a 

 certain distance of the vibrating laminae, and a certain length or form of the tube 

 above which is most favorable to the production of each note; and the downward 

 movement of the whole vocal organ, which takes place when we are sounding deep 

 notes, and its rise during the elevation of the tones, have been supposed to have 

 the purpose of making this adjustment in the length of the trachea ; but this 

 requires the supposition that the real length of the trachea is shortened whilst it 

 appears extended for which there seems no foundation. It is considered by 

 Mr. Wheatstone that the column of air in the trachea may divide itself into 

 " harmonic lengths," and may produce a reciprocation of the tone given by the 

 vocal ligaments ( 899) ; and in this manner he considers that the falsetto notes 

 are to be explained. It may be added, that the partial closing of the epiglottis 

 seems to assist in the production of deep notes, just as the partial covering of 

 the top of a short pipe fixed to a reed will lower its tone; and that something 

 of this kind takes place during natural vocalization, would" appear from the 

 retraction and depression of the tongue, which accompany the lowering of the 

 front of the head, when the very lowest notes are being sounded. The experi- 

 ments of Savart have shown, that a cavity which only responds to a shrill note, 

 when its walls are firm and dry, may be made to afford a great variety of lower 

 tones when its walls are moistened and relaxed in various degrees. This obser- 

 vation may probably be applied also to the trachea. 



935. The falsetto is a peculiar modification of the voice, differing from the 

 " chest voice," not merely in the higher pitch of its notes, but also in their 

 quality ; its tones being less reedy, and more like the " harmonic notes" of 

 stringed and wind instruments. In some individuals, the chest voice passes 

 by imperceptible gradations into the falsetto, whilst in others the transition is 

 abrupt ; and some persons can sound the same notes in the two different regis- 

 ters, these notes forming the upper part of the scale of the chest voice, and the 

 lower part of the falsetto. Thus, a gentleman of the author's acquaintance has 

 a bass voice of a harsh, reedy character, ranging from the D below the bass 

 cleff to the D above it (two octaves) ; whilst his falsetto, which is remarkable 

 for its clearness and smoothness, ranges from the A on the highest line of the 

 bass cleff to the E in the highest space of the treble cleff. Thus, there are five 

 notes common to the two registers, and the entire voice ranges through more 

 than three octaves ; but from want of a gradual passage from one to the other, 

 this gentleman can only sing bass parts with his chest voice, or alto parts with 

 his falsetto, the tenor scale extending above the range of one, and below that of 

 the other. With regard to the theory of the production of the falsetto voice, 

 there has been considerable difference of opinion amongst Physiologists ; and it 

 cannot be regarded as fully determined. By Magendie and Mayo it was main- 

 tained that these tones are produced by the vibration of the vocal cords along 



