“If we emit veiled and feeble sounds, the larynx opens at the
notes do re me (c d e), and we see the glottis agitated by
large and loose vibrations throughout its entire extent. Its
lips comprehend in their length the anterior apophyses of the
arytenoid cartilages and the vocal chords; but, I repeat it,
there remains no triangular space.
“As the sounds ascend, the apophyses, which are slightly
rounded on their internal side, by a gradual apposition
commencing at the back encroach on the length of the glottis,
and as soon as we reach the sounds si do (b c¹) they finish
by touching each other throughout their whole extent; but
their summits are only solidly fixed one against the other
at the notes do re (c♯¹ d¹). In some organs these summits are
a little vacillating when they form the posterior end of the
glottis, and two or three half-tones which are formed show
a certain want of purity and strength, which is very well
known to singers. From do re (c♯¹ d¹) the vibrations, having
become rounder and purer, are accomplished by _the vocal
ligaments alone_, up to the end of the register.
“The glottis at this moment presents the aspect of a line
slightly swelled towards its middle, the length of which
diminishes still more as the voice ascends. We also see that
the cavity of the larynx has become very small, and that the
superior ligaments have contracted the extent of the ellipse
to less than one-half.
“Thus the organs act with a double difference: 1. The cavity of
the larynx contracts itself more when the voice is intense than
when it is feeble. 2. The superior ligaments are contracted, so
as to reduce the small diameter of the ellipse to a width of two
or three lines. But however powerful these contractions may be,
neither the cartilages of Wrisberg, nor the superior ligaments
themselves, ever close sufficiently to prevent the passage of
the air, or even to render it difficult. This fact, which is
verified also with regard to the falsetto and head registers,
suffices to prove that the superior ligaments do not fill a
generative part in the formation of the voice. We may draw the
same conclusion by considering the position occupied by the
somewhat feeble muscles which correspond to these ligaments;
they cover externally the extremity of the diverging fibres of
the thyro-arytenoid muscles, and take part especially in the
contractions of the cavity of the larynx during the formation
of the high notes of the chest and head registers.