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CHAPTER IV |
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CONCEPTS OF PHONATION |
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D
efinition: Phonation is the act or process of generating vocal sound; it is the inception of vocal tone at its point of production in the larynx. More explicitly, phonation is the vibratory activity of the vocal cords so as to produce pulsations sufficiently rapid to
cause the sensation of tone. When these tones are sustained, they form the substance of the singing voice. (W) The larynx is the organ which produces vocal sound. It is situated at the top-most ring cartilage of the trachea (wind-pipe) and consists of adjustable cartilages, muscles and membranes which together operate the valve-like mechanism of the vocal cords. [Negus 418]
The weal cords (a misnomer), also more accurately called vocal bands* folds, tips, cushions, ledges, ligaments, shelves, muscles, processes, edges* consist of a pair of muscular folds that project into the cavity of the larynx. (The so-called false cords are for fixation and distension of the laryngeal ventricles and are not directly affected in phonation. [Hemery 2%St p. 55]) The true vocal cords can be tensed and drawn together (approximated) along their exposed edges so that the upward flow of breath between them causes them to vibrate, producing voice. "The vocal cords are the only parts of the larynx with any important function in phona-tion." [Negus op. cit.] The glottis is the aperture or chink existing between the vocal lips (cords) when they are drawn apart in normal respiration or when they are forced apart by the expiring breath stream during phonation. "The glottis can be opened, narrowed or closed . . . through the action of muscles controlling the arytenoid or adjusting cartilages." (W) The term glottis (glottal) is also sometimes used to refer to the vibrating edges of the vocal lips (cords).
Descriptions of phonation are often complicated by the presence of technical terms used to describe anatomical structures in the vocal tract. In the discussions which follow, this terminology is simplified to afford greater intelligibility of subject matter. Definitions and technical terms |
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