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Our Surroundings 



chamber in the instrument from which the air is removed by 

 means of a pump which is operated by the feet or by electricity. 

 Connected with this chamber is a metal tube, known as a tracker 

 bar, in which are a number of holes. Air entering one of these 

 holes causes a hammer to strike a certain string in the instru- 

 ment, thus producing a certain note. When the piano player 

 is in use, a partial vacuum is maintained in the chamber, and so 

 the pressure of the atmosphere tends to force air into each of 

 the holes and to operate its hammer. A perforated strip of paper, 

 the record of the music to be played, is passed across the holes, 

 and only the holes over which the perforations pass are exposed 

 to the pressure of the air. By this means any note, or combina- 

 tions of notes, can be played, and thus music is produced. 



A SYMPHONY ORCHESTRA 



Syracuse Symphony Orchestra. 



Locate several types of musical instruments and tell how each produces sound. 



The Voice. The human voice is produced in a box-like 

 structure, called the larynx, located at the top of the windpipe. 

 The lump on the front of the neck, popularly spoken of as Adam's 

 apple, is part of this larynx or voice-box. 



In the larynx are the vocal cords, consisting of two thin pro- 

 jecting membranes of elastic tissue, between which there is a 

 narrow opening called the glottis. In breathing, these membranes 

 are very loose and air passes between them without causing sound. 

 In producing sounds these membranes, or vocal cords, are 

 brought close together by muscular action and made more or less 



