FIG. 559,-view of the upper part of the 





CH. LV.] THE VOICE 759 



spends to the vocal cords in the air-chamber composed of the trachea 

 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 pitched 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 ten- 

 sion, and diminishes with the length of 



the string. The vocal cords of a woman &ote. ^ Epiglottis ; s, tubercles of the 



v /> r. cartilages of Santorini ; a. arytenoid 



are snorter tnan tnose or a man, nence cartilages; z, base of the tongue; 

 the higher pitched voice of women. fySZ^f waU of the pharynx ' 

 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- 

 ments do not lend themselves to this form of graphic record, but their 

 vibrations can be rendered visible by allowing them to act on a small 

 sensitive gas-flame ; this bobs up and down, and if the reflection of 

 this flame is allowed to fall on a series of mirrors, the top of the con- 

 tinuous image formed is seen to present waves. The mirrors are 

 usually arranged on the four lateral sides of a cube which is rapidly 

 rotated. If one sings a note on to the membrane in the side of the 

 gas-chamber with which the flame is in connection, the waves seen 

 are not simple up and down ones, but the primary large waves are 



