COMPASS OP THE VOICE.] 



UNDTTLATORY FORCES. ACOUSTICS. 



285 



appears to exist in the vocal apparatus must be syn- 

 chronous. * * * It might possibly oe objected 

 to the idea of this twofold action, that the production 

 of sound by the vocal cords is sufficiently accounted for 

 by supposing them to vibrate merely as elastic tongues ; 

 but then it is found by experiment, that by artificially 

 dividing their length into two ventral segments, there 

 results the octave of the fundamental note, which proves 

 that at all events they vibrate as cords. In conclusion, 

 we must bear in mind the vast difference between 

 natural and artificial mechanism ; and however compli- 

 cated a problem it may be to determine that constitution 

 of the vocal apparatus, by which the thyro-arytenoid 

 ligaments may simultaneously obey the laws of cords and 

 tongues, yet, to a physiologist who is accustomed to 

 meet with the most admirable contrivances and com- 

 binations in the animal frame, the difficulty of finding 

 a strictly mathematical solution is, in such a case, no 

 objection to its truth, -when the facts, as far as they 

 have been observed, are decidedly favourable to its 

 reality."* 



It was before hinted at, that the vibrations of the 

 walls of the tubes through which the voice is conducted, 

 may, in some degree, influence its sound. In rigid 

 tubes, the vibrations depend on the nature of the im- 

 pulse propagated in the air within, jointly with the 

 length of the pipe. So long, then, as the length of the 

 pipe remains the same, and no change takes place on the 

 material of its walls, the pitch of the sound produced 

 he undulations of the air within, remains unaffected. 

 The dimensions of the windpipe, such as its length and 

 diameter, are invariable ; and, were the height of the 

 larynx, and the dimensions of the bifid tube (the nose 

 and mouth), through which the air issues after the for- 

 mation of voice, equally invariable, the vibrations of 

 these parts would produce no change on the pitch of 

 the voice, the quantities being constant for each tone 

 produced in the glottis. It has been found, that by 

 taking tubes composed of layers of paper, of constant 

 length, but varied in thickness, graver sounds were pro- 

 duced as the parietes became thinner, and that the 

 gravity of the sound was increased by moistening and 

 relaxing the sides of the tubes. It was before noticed, 

 that the windpipe is capable of being drawn upwards 

 from the chest, to a small extent, while the larynx is 

 elevated ; and that this tube admits of being diminished 

 in its diameter by about one-third part. Moreover, the 

 pharynx, the mouth, and the nasal cavities are also 

 susceptible of various modifications of diameter ; so that 

 the pipe, so to speak, near the middle of which the vocal 

 sound is produced, is in a very different condition from 

 a rigid tube. Hence, it has been concluded that pro- 

 vision is made for an invariable adaptation between the 

 amount of tension, the vibrating length of the vocal 

 ligaments, and the walls of the vocal tube, for the pro- 

 duction of the ordinary tones of the voice. It appears, 

 indeed, to have been proved that the vocal tube is so 

 short, that were it rigid, it could not influence the pitch 

 of the note which the glottis originates. But its want 

 of length is compensated for by the relaxation of its 

 walls, so that it comes to vibrate synchronously, and HO 

 to give forth sounds equally grave with those of the 

 glottis. Its effect, therefore, is to add to the force of 

 the tone, which, without its aid, would have been found 

 to possess less intensity. 



After considering this subject in every possible light, 

 the conclusion appears to be that to which Mr. Bishop 

 has come; namely, that the evidence shows "the vocal 

 apparatus to bo influenced by the air expelled from the 

 chest, in precisely the same way as if it were a stretched 

 cord, a reed, or a vibrating tube. Why, then," he 

 continues, "should we hesitate to adopt the obvious 

 conclusion, that the vocal organs do, in fact, combine the 

 properties of these various instruments, and are thus the 

 perfect types of which these instruments are only im- 

 perfect imitations V 



Singing. The notes of the human voice are capable 

 of being produced in three separate kinds of sequence. 

 Cyclopadia of Phyrioloyy : article " Voicj" p. MSI. 



In ordinary speaking, the successive notes have nearly 

 all the same pitch. This kind of succession, then, is 

 properly termed the monotonous. Some deviation from 

 this monotony occasionally arises, as when certain syl- 

 lables receive a higher intonation for the sake of accent , 

 and when, in reading or reciting poetry, rhythm is added 

 to the accent. In these cases, however, the deviation 

 from monotony of pitch is too slight to require a sepa- 

 rate head. In the expression of passion, accompanied 

 by vehement exercise of the voice, there is heard a 

 sudden transition from high to low notes, or the reverse. 

 This, then, constitutes the second kind of sequence in 

 the notes of the human voice. Musical notes constitute 

 the third mode of sequence. In music, the sound has 

 the requisite number of vibrations ; and as the sounds 

 succeed each other, they exhibit that relative proportion 

 in the number of vibrations wliich jointly characterise 

 the notes of the musical scale. Of the adaptation of 

 one sound to succeed another, so as to preserve the 

 musical character of the succession, the human ear is 

 the only original standard. 



Compass of the Voice. In singers, the compass of the 

 voice extends through two or three octaves. When the 

 male and female voices are taken together, the entire 

 scale of the human voice includes four octaves. The 

 lowest note of the female voice is about an octavo higher 

 than the lowest of the male voice; the highest of the 

 female voice is about an octave higher than the highest 

 of the male. The first four notes of all voices are most 

 commonly weak. There are two kinds of male voice, 

 the bass and tenor ; and two kinds of female voice, the 

 contralto and soprano. The essential distinction between 

 these voices does not consist in their difference of pitch. 

 The bass voice commonly reaches lower than the tenor, 

 and its strength lies in the low notes ; while the tenor 

 voice extends higher than the bass. The contralto voice 

 has most commonly lower 



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I 



8 



notes than the soprano, 

 and is strongest in the 

 lower notes of the fe- ^ 

 male voice; while the 

 soprano voice reaches ^ 

 higher in the scale. It 

 is found, however, that 2> 

 bass singers can some- g 

 times go very high, and ^ 

 the contralto not unfre- ~ 

 quently sings the high ? , i 

 notes like soprano sing- 

 ers. The difference be- ^ 

 tween the bass and tenor "* 

 voice, and between the 

 contralto and soprano, is 

 plainly, then, not one of 

 pitch, but consists in the 

 peculiar timbre or quality 

 of the notes ; for these 

 several voices are distin- 

 guished from each other, 

 even when sounding the 

 same note. The quali- 

 ties of the baritone and 

 mezzo-soprano voices arc ' 

 less marked ; the bari- 

 tone being intermediate . 

 between the bass and "^ 

 tenor, tLe mezzo-soprano 

 between the alto and 

 soprano. 



The difference of pitch 

 between the male and female voice, is connected with 

 the different length of the vocal ligaments in the 

 two sexes. It appears that the lengths of the male 

 and female vocal cords in repose, are nearly as 7 to 

 5, and in tension as 3 to 2 ; in boys at tho ago of 

 fourteen, the length is to that of females, after puberty, 

 as 6-25 to 7 so that the .pitch of the voice is nearly the 

 same. The difference in the quality of the female v: ice, 

 as compared with that of the male, is owing to the 



