VOICE AND SPEECH 



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the hyoid bone (to be felt in the neck above it). The crico- 

 thyroid muscle, being unable to depress the thyroid, raises the 

 front of the cricoid cartilage, tilts back the arytenoids, tightens 

 the vocal cords. As the voice ascends the scale, the tension 

 of the cords is progressively increased, and their vibrations 

 rendered proportionately more rapid. The range of the human 

 voice is about three and a half octaves ; of individual voices 

 about two octaves ; if the shrill cry of a baby, which may reach 

 the third G above the middle C, or even higher (E"" or F""), 



FIG. 46. THE LARYNX FROM THE RIGHT SIDE. 



From above downwards : the hyoid bone, thyro-hyoid membrane, thyroid cartilage, cricoid 

 cartilage, trachea. The upper and posterior angle of the wing of the thyroid cartilage is 

 suspended from the hyoid bone ; its lower and posterior angle articulated with the cricoid 

 cartilage. On the summit of the cricoid cartilage it articulates the arytenoid. Dotted 

 lines indicate the position of the vocal cord. The crico-thyroid muscle, which raises the 

 front of the cricoid, tilting the arytenoid cartilage backwards and tightening the vocal cord, 

 extends, fan-like, from the front of the cricoid to the lower border of the wing of the 

 thyroid. 



be excluded. Exceptional voices have a range far greater 

 than two octaves. Falsetto voice is produced by throwing 

 half of the vocal cord out of vibration (the way in which this 

 is accomplished is not clear), and at the same time raising the 

 back of the tongue to the wall of the throat in such a manner as 

 to cut off all the lower part of the upper resonating chamber, 

 leaving it only the mouth and the cavities of the nose. 



So far the mechanism of voice is easily understood. As the 

 scale is ascended, the vocal cords are progressively tightened 

 by the contraction of the crico-thyroid muscles. But an analysis 



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