EVOLUTION OF THE SPEECH ORGANS OF MAN

Abstract

Human speech depends primarily on the production of sound in the larynx, an organ which corresponds to the reed in various musical instruments or to the sound box of a gramophone. To produce this sound bellows are required to blow air through the glottis; these bellows are provided by the lungs, encased in the thoracic cavity, made up of the mobile ribs and the diaphragm. The compound sound produced in the larynx is modified by resonators above and below the glottis and is further altered by various stops, which can interrupt the vibrating column of air or direct it mostly through the nose or out of the mouth, independently or synchronously. These stops are the vocal cords and ventricular bands, the soft palate and nasopharyngeal sphincter, the tongue and fauces and the lips. All of these constituents of the speech mechanism are controlled and coordinated by the brain and are