TONE OF THE VOICE. 465 



In later years, several new views have been propounded on this 

 subject, and chiefly by MM. Cuvier, Dutrochet, Magendie, Biot, Savart, 

 &c., men of the highest eminence in various departments of physical 

 science. 



M. Cuvier 1 attributes variety of tones, in the first place, to varied 

 length of the vocal tube, and to differences in size of the aperture of the 

 glottis; and, secondly, to the shape and condition of the external aper- 

 ture of the tube, that is, of the lips and nose. The larynx he regards 

 as a wind instrument, in which the inferior ligaments act, not as cords, 

 but like the reed of a clarionet, or the lame of an organ pipe. The 

 lungs and their external muscular apparatus constitute the reservoir of 

 air and bellows ; the trachea conducts the air, and the glottis is the 

 embouchure with its reed; the mouth, and the whole of the space com- 

 prised between the glottis and the opening of the lips, being the body 

 of the instrument ; whilst the openings of the nostrils are lateral holes, 

 that permit the size of the instrument to be varied. The tones are 

 changed by three causes of a similar character to those that modify 

 them in musical instruments ; the length of the body of the instru- 

 ment, and the variableness of the embouchure, and of the aperture at 

 the lower extremity of the instrument. The condition of the external 

 aperture of the vocal tube has, doubtless, much to do with the charac- 

 ter of the tone produced by the glottis ; but its influence appears to be 

 greatly limited to giving it rotundity, volume, or the contrary, as 

 will be seen hereafter ; although analogy would seem to show, that the 

 tone may be varied by more or less closure of the aperture. Many 

 different notes can be produced in the first joint of a flute, if we modify 

 the size of the opening at its extremity by passing the thumb more or 

 less within it. It is doubtful, however, whether in man the altered 

 size of the external aperture, or the elongation or decurtation of the 

 tube exerts as much influence in the production of acute or grave sounds 

 as Cuvier imagined. 



M. Dutrochet 2 again, believes, that the vocal tube has no influence in 

 the production of tones, and that the larynx is a simple vibrating in- 

 strument, uncomplicated with a tube, the vocal sound being caused by 

 the vibrations into which the vocal cords are thrown by the impulse of 

 the expired air. In his experiments, he saw the inferior ligaments 

 vibrate ; and he concludes, that the tone of the voice depends upon the 

 number of- vibrations of those ligaments in a given time, and that their 

 number will necessarily vary greatly, as the dimensions of the liga- 

 ments, that is, their length and thickness, and their elasticity, are 

 susceptible of incessant changes, by the contraction of the thyro-aryte- 

 noid muscle, of which they are essentially composed, the ligament, 

 covering the muscle, serving only " to prevent the collisions of the mus- 

 cles at the time of vibration," as well as by that of the other intrinsic 

 muscles of the larynx. 



MM. Biot and Magendie 3 dissent from M. Dutrochet in some important 



1 Le9ons d' Anatomic Compares, torn. iv. 445. 



a Mem. pour servir a 1'Histoire Anat. et Physiol. des Vegetaux et des Anirnaux, t. ii., 

 Paris, 1837 ; and Adelon, Physiologic de 1'Homme, edit, cit., ii. 239. 

 a Precis Elementaire, &c., i. 248. 



VOL. i. 30 



