490 THE VOICE 



tone than a small one, while a tightly stretched string gives a 

 higher note than one of the same size but less taut. 



(c) Quality. A piano string and a violin string may be of the 

 same size and tension and be struck with the same force. In 

 that event they will give the same pitch and have the same loud- 

 ness. We are still able, however, to detect that one is a violin 

 string and the other a piano string. This difference between 

 sound producers of the same pitch and loudness we call quality. It 

 is due to the fact that few bodies vibrate simply and as a whole. 

 Most bodies have not only a vibration as a whole which gives what 

 is called the fundamental note, but separate parts of the bodies 

 vibrate more or less independently producing distinct waves, 

 which combine with the fundamental and are called overtones. 

 No two bodies produce these overtones in the same way, owing to 

 differences in size, shape, or material, and hence the complex 

 tone produced is characteristic of each vibrating body and enables 

 us to distinguish between various sources of sound. 



Resonance. — The quality of a sound may be changed and its 

 loudness increased by reenforcing the original vibration with 

 others of a similar pitch. Thus, a violin string stretched over a 

 sounding board sets the air of the sounding board in vibrations 

 of the same pitch, reenforcing and altering the quality and loud- 

 ness of the original string vibrations. Such reenforcement is 

 called resonance and the reenforcing body is called a resonator. 



Application of sound laws to vocalizing. — The vocal cords 

 furnish the vibrating bodies which are struck or set in 

 vibration by the expired air. The air cavities of the 

 throat, pharynx, nasal cavity, and mouth are the 

 resonators. 



By movements of the larynx cartilages the tension of 

 these cords can be changed, and tlius the pitch is regulated. 

 The force with which the air is expired determines the 

 width of vibration and the loudness, while loudness and 

 the quality of the tones may be still further modified by 

 changing the shape of the resonating cavities. 



