Experimental physiology / by Sir Edward Sharpey-Schafer.

  • Edward Albert Sharpey-Schäfer
Date:
1927
Catalogue details

Licence: In copyright

Credit: Experimental physiology / by Sir Edward Sharpey-Schafer. Source: Wellcome Collection.

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    The Production of Vocal Sounds. Analysis of Sounds. Audition. Semicircular Canals Use of the laryngoscope.—The laryngoscope consists of a small circular plane mirror fixed to a handle at a suitable angle; a large concave mirror with a hole in the centre is strapped to the operator’s forehead. Method of procedure.—Practise first on an artificial model of the larynx and afterwards on the living subject. The latter is placed on a stool with a lamp over his right shoulder, a little above the level of his mouth. The observer sits opposite and close to the subject with the large mirror attached to his forehead. The subject is asked to open his mouth, incline his head slightly backwards, protrude his tongue, and hold it down with a handkerchief. The observer manoeuvres his head until the back of the subject’s throat is brightly illuminated; he then takes the small mirror in his right hand, warms it slightly in a flame to prevent moisture condensing on its surface (the back of the mirror should be just perceptibly warm to the cheek), and, holding the handle as one does a pen, pushes it horizontally back- wards until it touches the uvula. First the dorsum of the tongue is seen in the mirror, then, as the handle is depressed, the epiglottis; then the glottis and vocal cords come into view. The image of the larynx thus obtained is an inverted one. In ordinary breathing the glottis is open ; if the patient is asked to sound a high note the vocal cords may be seen to come together and to vibrate, and if he is asked to take a deep breath they separate ; the interior of the trachea and even its bifurcation may then be seen through the widely open glottis. Any tendency to retch when the mirror comes in contact with the soft palate may be diminished by the application of a solution of cocaine to the mucous membrane. The movements of the laryngeal cartilages are studied in a model which represents them articulated together. The action of the muscles can be imitated by threads, and the vocal cords by thin flat rubber bands stretched between the thyroid and arytenoids. The production of vowel sounds.—Notice that the production of the vowel sounds (ah, eh, ee, o, oo) is accompanied by changes in the
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