372 



It appears then, that, rejecting the opposite and exclusive explanations 

 of Ferrein and Doclart, we are to consider the larynx as an instrument 

 combining the advantages, and exhibiting the double mechanism of wind 

 and stringed instruments ; it is on this account that it surpasses all mu- 

 sical instruments, by the extent the perfection, and above all, by the in- 

 exhaustible variety of its effects. There is no one, that has heard, at a 

 concert, a solo on the French horn by an able performer, but has been 

 struck with the resemblance of the effects of this instrument, and those of 

 the human voice. It is because the vibrating body at the mouth piece of 

 the instrument, is alive : it is because the lips, like the sides of the glot- 

 tis, are moveable, the opening of the mouth dilates and contracts, and, at 

 the same time, its edges are relaxed or stiffened by the contraction of the 

 muscles of the lips. 



The modifications of the voice, depend, not only on the varied sizes of 

 the opening of the glottis, and on the tension of its ligaments, but further 

 on the. degree of length of the trachea. The singer who runs down the 

 whole scale of sounds, from highest to lowest, visibly, shortens the neck 

 and the trachea, whilst in ascending, he stretches them out. 



The force of the voice* depends on the volume of air that may be ex- 

 pelled from the lungs at once, and on the degree of aptness, in the pa- 

 rietes of the canals by which it is given out. Birds, whose body is all 

 aerial, have a voice very strong for their bulk. Their trachea) furnished 

 with a double larynx, is almostf entirely cartilaginous. It is especially so 

 in certain screaming birds, as the jay, and some others; whilst it is nearly 

 all membranous in the hedge-hog, a small quadruped, whose cries are 

 almost imperceptible. 



The hissing of serpents, and the croaking of frogs are heard to some 

 distance, because these creatures can send out a large quantity of air, at 

 once, from their vesicular lungs, and in the last, because the vocal strings 

 are completely insulated from the coats of the larynx, with which in other 

 animals, they are continuous. } 



The voice of men is strong according to the capacity of the chest. It 

 is always weaker after meals, when the stomach and intestines, distended 

 with food, push up the diaphragm and resist its descent. The voice, 

 formed in the passage of the air along the glottis, acquires much force 

 and intensity, becomes much more sonorous, by the reverberations of the 

 sound in the mouth and in the nasal cavities. It is weakened and disa- 

 greeably impaired, when a polypus of the nasal canals, or of the throat, 

 or the destruction of the roof of the mouth, prevents the air from passing 

 along the nasal canals, and their various sinuses. The voice is then said 

 to be nasal, though, in truth, it suffers from want of the modifications it 

 should receive in the cavities belonging to the nose. 



CXCVI. Of speech. To whisp.tr is to articulate very weak sounds, 

 which, in truth, deserve not the name of voice, since they scarcely exceed 

 the sound, which always accompanies the passage of air in expiration. 

 Man only can articulate sound, and enjoys the gift of speech. The par- 

 ticular disposition of the mouth, of the tongue, and lips makes all pronun- 

 ciation impossible to quadrupeds. The monkey, in whom these parts 



* Sailors, and those that live on the banks of great rivers, have commonly strong- 

 voices from being obliged to overpower, with the voice, the noise of the waves, which 

 bas constrained them to a great habitual exertion of its organs. Authors Note. 

 See the Memoirs of M. Ctivier on the double Jarynx, and on the voice of the birds. lb. 



