470 MUSCULAR MOTION. 



is first excited at the embouchure, which throws the column of air, 

 within the instrument, into vibration. Every sound, indeed, produced 

 at the orifice of a column of air, throws it into vibration, provided its 

 dimensions be adapted to the length of the waves produced directly: 

 hence the utility of a musical pipe having parietes susceptible of vary- 

 ing in size and tension, whatever may be the character of its embou- 

 chure. Lastly. The fundamental note of a tube closed at one end, 

 whose diameter is every where the same, is an octave lower than the 

 sound of the same tube, when open at both extremities. But this is 

 not the case with tubes that are of unequal diameter, conical and pyra- 

 midal, &c., when made to vibrate at their narrowest part. The tone 

 produced in such case increases in graveness, according to the difference 

 between its narrow and expanded portions. 



These different physical conditions M. Savart invokes to account for 

 the different tones of the human voice, under the theory, that the vocal 

 organ composed of the larynx, pharynx, and mouth forms a conical 

 tube, in which the air is set in vibration by a movement similar to that 

 which prevails in organ pipes. The trachea is terminated above by a 

 cleft the glottis which is the inferior aperture of the vocal instru- 

 ment. This cleft, which is capable of being rendered more or less nar- 

 row, plays the same part as the lumiere des twjaux d bouche or narrow 

 space in the organ pipe, at the edge of the biseau or languette, along 

 which the air passes. The air clears it, traverses the ventricles of the 

 larynx or cavity of the instrument, and strikes the superior ligaments. 

 These surround the upper aperture of the instrument, and fulfil the 

 same function as the biseau of the organ pipe. The air, contained in 

 the interior of the larynx, now vibrates, and sound is produced. This 

 sound acquires intensity, from the waves that constitute it extending 

 into the vocal tube above the larynx, and exciting in the column of 

 air filling it, a movement similar to that occasioned in the tube of a 

 flute; except, that the tone is susceptible of much variation, because 

 the larynx, being a short tube, can give rise to various tones by simple 

 modification in the velocity of the air sent through it : moreover, the 

 vocal tube has the same power, its parietes being membranous, of a 

 vibratory nature, and capable of different degrees of tension. The 

 inferior or outer part of the vocal tube is equally constituted of elastic 

 parietes, susceptible of varied tension; and the mouth, by modifying the 

 dimensions of the column of air within the tube, exerts an influence on 

 the number of vibrations, which the column is capable of experiencing; 

 whilst the lips can convert the channel at pleasure into an open or closed 

 conical tube. Certain sounds, M. Savart affirms, are produced alto- 

 gether in the ventricles of the larynx, as those of pain, and the falsetto 

 voice, for example. They can be elicited when the vocal tube has been 

 removed; and there are animals, in which the vocal organ is reduced to 

 the ventricles of the larynx, frogs for example. Savart, consequently, 

 considers, that the human vocal organ bears in its essential parts, C C, 

 B B, Fig. 197, a striking analogy to the action of the bird-call; and, 

 in this way, he explains the use of the superior ligaments C C, which 

 are entirely overlooked in the different theories of the voice previously 

 propounded. 



