separated, leaving free vent for air through the glottis; consequently
there is no vibration and no sound produced by the cords. (4) The soft
vocal note, or aspirate, shows that the chink of the glottis is not
completely closed, and especially the rima respiratoria (the space between
the vocal processes of the pyramidal cartilages.) (5) Strong vocal note,
produced in singing notes of the lower register. (6) Strong vocal note,
produced in singing notes of the higher register.]

Musical notes are comprised between 27 and 4000 vibrations per second. The
extent and limit of the voice may be given as between C 65 vibrations per
second and f''' 1417 vibrations per second, but this is most exceptional,
it is seldom above c''' 1044 per second. The compass of a well-developed
singer is about two to two and a half octaves. The normal pitch, usually
called the "diapason normal," is that of a tuning-fork giving 433
vibrations per second. Now what does the laryngoscope teach regarding the
change occurring in the vocal cords during the singing of the two to two
and a half octaves? If the vocal cords are observed by means of the
laryngoscope during phonation, no change is _seen_, owing to the rapidity
of the vibrations, although a scale of an octave may be sung; in the lower
notes, however, the vocal cords are seen not so closely approximated as in
the very high notes. This may account for the difficulty experienced in
singing high notes piano. Sir Felix Semon in a Friday evening lecture at
the Royal Institution showed some remarkable photographs, by Dr. French, of
the larynx of two great singers, a contralto and a high soprano, during
vocalisation, which exhibit changes in the length of the vocal cords and in
the size of the slit between them. Moreover, the photographs show that the
vocal cords at the break from the lower to the upper register exhibit
characteristic changes.

[Illustration: Fig. 11]