CHAPTER XVII 

 VOICE AND SPEECH 



Physiological anatomy of the vocal organs Muscles of the larynx Crico-thyroid muscles 



Arytenoid muscle Lateral crico-arytenoid muscles Thyro-arytenoid muscles 

 Mechanism of the production of the voice Movements of the glottis during phonation 



Action of the intrinsic muscles of the larynx in phonation Action of accessory vocal 

 organs Laryngeal mechanism of the vocal registers Vocal registers in the male 

 Vocal registers in the female Mechanism of speech Vowels Consonants The 

 phonograph and telephone. 



THE principal organ concerned in the production of the voice is the 

 larynx. The accessory organs are the lungs, trachea, expiratory mus- 

 cles, the mouth and the resonant cavities about the face. The lungs 

 furnish the air by which the vocal chords are thrown into vibration, and 

 the mechanism of this action involves merely modifications of expira- 

 tion. By the action of the expiratory muscles the intensity of vocal 

 sounds is regulated. The trachea not only conducts the air to the 

 larynx, but it may assist, by resonance, in modifying the quality of the 

 voice. Most of the variations in tone and quality, however, are effected 

 by the action of the larynx itself and of the resonant cavities' situated 

 above. 



Physiological Anatomy of the Vocal Organs. The vocal chords are 

 stretched across the superior opening of the larynx from before back- 

 ward. They consist of two -pairs. The superior, called the false vocal 

 chords, or the ventricular bands, are not concerned in the production of 

 the voice. They are less prominent than the inferior chords, although 

 they have nearly the same direction. They are covered with a thin 

 mucous membrane that is closely adherent to the subjacent tissue. 

 The chords are composed of ordinary fibrous tissue with a few elastic 

 fibres. 



The true vocal chords, or vocal bands, are situated just below the 

 superior chords. Their anterior attachments are near together, at the 

 middle of the thyroid cartilage, and are immovable. Posteriorly they 

 are attached to the movable arytenoid cartilages ; and by the action of 

 certain muscles their tension may be modified and the chink of the 

 glottis may be opened or closed. These are much larger than the false 

 vocal chords and they contain a great number of elastic fibres. Like 



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