316 SIR CHARLES BELL ON THE ORGANS OF THE HUMAN VOICE. 
lation defective ; 6th, That the removal of the cells of the face, equally with 
their obstruction, deprives the voice of its body and clearness ; 7th, In 
nervous relaxation of the muscles of the throat, there is sound ; but its nature 
evinces how much the proper action of the muscles is necessary to the voice. 
Recapitulation. 
It is curious, and not without its use, to observe how many parts must con- 
form, and how many actions must accurately correspond, to produce the sim- 
plest sound ; and how many additional combinations there must be for the 
formation of articulate voice. 
As we may audibly breathe through a trumpet without producing a note of 
music, so we breathe without the tremor of the glottis to produce voice pro- 
perly, but only the whisper. To vocalize the breath, there must not only be 
a certain strength of impulse in the column of air, but there must be an ad- 
justment of the vocal chords in the glottis. The mere impulse of the breath, 
however forcible, as in sneezing, does not necessarily move the chords of the 
glottis. 
The chordae vocales being strung by the action of their muscles in corre- 
spondence with the forcible expulsion of the breath, they vibrate : this vibra- 
tion is reverberated on the column of air ; and by an adjustment of the passages 
above, there is a correspondence between the motions of the glottis and the 
vibrations of the column of air. The breath, thus vocalized, forms the several 
open sounds or vowels by the change or modulation of the passages : for by 
the more or less contraction and dilatation of the tube, these sounds are modi- 
fied ; the vibrating air being differently directed, and impelled against different 
portions of the tube. 
The musical notes are in the same way produced by changes in the force 
with which the voice is propelled, the degree of tension in the chordae vocales, 
and the modulation or change in the form of the open passages. There is no- 
thing more surprising than the precision with which the notes of the human 
voice are produced, as when we hear it rising above the sound of the church 
organ, the notes more liquid and distinct, and descending in a solfeggio of 
notes and half-notes, as if each arose from a different pipe, or were struck on 
a distinct instrument. Yet these falls are consequent on muscular action, which 
