M. Savart on the Mechanism of the Human Voice. 205 



become one of those which the voice can produce. A similar 

 tube, open at both ends, gives the sound ut 5 , and there are 

 many human voices which are no higher than la 4 which is 

 graver only by a third minor. If we shut a great part of the 

 base of the tube, the sound will, by this means, easily descend to 

 ut 4 , and even below it, and it would require to be lowered only 

 about an octave more, in order to equal the gravest sounds of 

 the human voice. But if we consider that the column of air 

 in the vocal tube is inclosed, particularly on the lower part, 

 by extensible sides, and which are themselves capable of vi- 

 brating and influencing the motion of the air by dividing it, 

 we may easily conceive, that the sound may be easily lowered 

 an octave more. If we construct, indeed, a pyramidal tube, 

 such as AB Fig. 11, nearly of the same length as the vocal 

 tube, viz. 4| inches, approaching to the same capacity, and 

 membranous in the lower third CD of its length, we may 

 make it produce all the sounds of an ordinary voice, either by 

 making the tension of the membranous part vary, or by shut- 

 ting more or less its great orifice, an aperture, however, being 

 always left. 



The only difference between this and the vocal tube con- 

 sists in the kind of embouchure. In the vocal tube it is an- 

 alogous to that of the instrument Fig. 7. The trachea TT ; , 

 Fig. 10, is terminated above by a slit which may be made 

 more or less narrow by the approach or recess of the aryte- 

 noid muscles, and by the contraction of the thyro-arytenoid 

 muscles, represented by BB / , Fig. 10. This aperture obvious- 

 ly performs the same part as the aperture in mouth-pieces. 

 The jet of air which comes out of them, traverses the interval 

 between the ventricles, and strikes against the superior liga- 

 ments OCX, which, though rounded, perform the same part as 

 the bevel in organ-pipes. The air in the ventricles VV then 

 enters into vibration, and yields a sound which, if it were insu- 

 lated, would be feeble, but it acquires intensity because the un- 

 dulations, which set out from the interval situated between the 

 superior ligaments CC, propagate themselves in the vocal tube 

 placed below, and these produce a kind of motion analogous 

 to that which exists in short, and partly membranous tubes. 



In order, however, that the definitive sound thus produ- 



