564 
MR. BISHOP ON THE PHYSIOLOGY 
of the highest note of the ordinary register, suddenly opens on the production of 
the first note of the falsetto register, and consequently the thyro-arytenoid ligaments 
are relaxed at the same moment the larynx falls, and the vocal tube is lengthened, 
although during these changes the tones become more acute. As soon as this has taken 
place, the larynx again rises as the voice becomes more acute. In a mezzo soprano 
voice endowed with a double falsetto, or third register consisting of several tones of 
each register, with the power of producing tones of the same pitch either of the ordi- 
nary or the falsetto quality, we observed that the larynx fell at the commencement of 
each register, and that the thyro-arytenoid ligaments were twice relaxed, but in a 
much smaller degree. These observations have since been verified by many musical 
persons. 
In order to explain the phenomena as connected with the production of falsetto 
tones, we must remember that at the highest note of the primary register, the 
crico-thyroid muscles are contracted as much as possible in closing the crico-thyroid 
chink, and therefore that no further tension of the vocal cords can take place. 
In this state of things the thyro-arytenoid muscles are at their maximum of elon- 
gation, and their transverse section is a minimum, consequently neither can a higher 
note be produced by an extension of the ligaments, nor are these muscles in a con- 
dition to affect the dimensions of the glottis ; hence the necessity of some alteration 
in the state of the larynx in order to effect the scale of the falsetto, which is an octave 
above the ordinary register, and to prevent the mere repetition of the same series of 
sounds. This alteration might be produced in two ways ; one of these is a partial 
closing of the aperture of the glottis caused by the action of the thyro-arytenoid 
muscles when they have returned to their ordinary condition, and are in a favourable 
state to produce that effect under the influence of the laryngeal nerves. For, let us 
suppose the larynx to be in the same state as at the commencement of the primary 
register, except that the chink of the glottis is half-closed ; the consequence will be 
that as only half the length of the ligaments can be made to vibrate, the octave of the 
lowest note in that register will result from the same tension which produced that 
note, and this will manifestly be repeated in consecutive notes of the range of the 
falsetto. This range is limited in general to a few notes, owing probably to the chink 
being soon completely closed by the stretching of the vocal cords. It is also owing 
to this partial closing of the glottis that a much less quantity of air is required for 
the falsetto than for the ordinary scale, which is proved by our being able to sustain 
a given note in the falsetto a much longer time than we can sustain the corresponding 
note in the primary register. The partial closing of the glottis was observed by 
Majendie in his experiments on the dog, and by Mayo in the human subject. An- 
other explanation was suggested by Gottfried Weber, namely, that the falsetto range 
is caused by a nodal division of the vocal cords producing harmonics of the funda- 
mental notes, by which means the glottis acquires the same pitch as if it were half- 
closed. If we consider the glottis as a reed, it is evident that since the number of 
