drawn. The parts of the palate from which the chalk has been removed show the points at which the tongue touched it. These marks on the artificial palate may then be examined at leisure. They may also be photographed if desired, or the marks may be copied on outline diagrams of the palate.
*42. The diagrams thus obtained are known as palatograms. The palatograms in this book have been drawn from observations made with vulcanite palates. The palates here used extend so as to cover the whole of the front teeth. The limits of the gums adjoining the front teeth are marked on the present diagrams by the dotted line (fig. 18, etc.).
CHAPTER V
BREATH AND VOICE
43. When the vocal chords (§ 34) are wide apart (i. e. when the glottis is open) and air passes between them, the sound produced is called breath; when they are drawn together and air is forced between them so that they vibrate (§ 34), the sound produced is called voice. Certain intermediate positions of the glottis give rise to the sounds known as whisper.
Fig. 4. The Larynx as seen through the laryngoscope.
A. Position for Breath. B. Position for Voice. TT. Tongue. VV. Vocal Chords. W. Windpipe.
44. The sound h (§ 328) is pure breath; the vowel sounds are pure voice.
45. Fig. 4 will make clear the positions of the vocal chords in the production of breath and voice. The diagrams show the larynx as seen from above through the laryngoscope.
*46. The Laryngoscope in its simplest form is a small circular mirror, about ¾ of an inch in diameter, which is fixed to a long handle at an angle of 120°
Fig. 5. The Laryngoscope.
When the instrument is held in the position shown in fig. 5 and inserted into the mouth so that the mirror is pressed against the soft palate as far back as possible, and is adjusted so that a strong light is reflected down the throat, the interior of the larynx is visible in the mirror.
*47. Breath and voice may be illustrated artificially by the following
