806 VOICE AND SPEECH [CH. LVII. 



No true vocal sound is produced at the posterior part of the 

 aperture of the glottis, namely, that which is formed by the space 

 between the arytenoid cartilages. 



8 The Voice. 



The human musical instrument is 

 often compared to a reed organ-pipe : 

 certainly the notes produced by such 

 pipes in the vox humana stop of organs 

 is very like the human voice. Here 

 FIG. 505. view of the upper part of the there is not only the vibration of a 



larynx as seen by means of the laryngo- pnlnm-n nf m'r Vmf alan nf a TAPP! whinh 

 scope during the utterance of a bass COiUmn 01 air, DUE aiSO 01 a reCQ, WHICH 



note, e, Epiglottis ; s, tubercles of the corresponds to the vocal cords in the 



cartilages of Santonni; a, arytenoid . r . , _ ,. . 



cartilages; z, base of the tongue; air-chamber composed of the trachea 

 ft^g***** <*"&*****' and the bronchial system beneath it. 



The pharynx, mouth, and nasal cavities 



above the glottis are resonating cavities, which, by alterations 

 in their shape and size, are able to pick out and emphasize 

 certain component parts of the fundamental tones produced in the 

 larynx. The natural voice is often called the chest voice. The 

 falsetto voice is differently explained by different observers; on 

 laryngoscopic examination, the glottis is found to be widely open, so 

 that there is an absence of chest resonance ; some have supposed 

 that the attachment of the thyro-arytenoid muscle to the vocal cord 

 renders it capable of acting like the finger on a violin string, 

 part of the cord being allowed to vibrate while the rest is held still. 

 Such a shortening of a vibrating string would produce a higher note 

 than is natural. 



Musical sounds differ from one another in three ways : 



1. In pitch. This depends on the rate of vibration ; and in the 

 case of a string, the pitch increases with the tension, and diminishes 

 with the length of the string. The vocal cords of a woman are shorter 

 than those of a man, hence the higher pitched voice of women. The 

 average length of the female cord is 11 '5 millimetres; this can be 

 stretched to 14; the male cord averages 15*5, and can be stretched 

 to 19*5 millimetres. 



2. In loudness. This depends on the amplitude of the vibrations, 

 and is increased by the force of the expiratory blast which sets the 

 cords in motion. 



3. In " timbre." This is the difference of character which dis- 

 tinguishes one voice, or one musical instrument, from another. It 

 is due to admixture of the primary vibrations with secondary vibra- 

 tions or overtones. If one takes a tracing of a tuning-fork on a 

 revolving cylinder, it writes a simple series of up and down waves 

 corresponding in rate to the note of the fork. Other musical instru- 



