chap, 



.} QUALITY OF MUSICAL SOUNDS. 



435 



phrase klang farbe, meaning sound tint, or sound 

 colour, while the French term is timbre, meaning 

 stamp. On what, then, does quality depend ] 

 Consider waves ; they differ in size, in rapidity or 

 frequence, but they also differ in form. Size is 

 equivalent to amplitude of vibration, i.e. loudness of 

 sound, and rapidity to the number of vibrations per 

 second, i.e. pitch of sound, while the form of the 

 wave is found to correspond to the quality of sound. 



Waves may be simple or compound ; if simple, 

 their form will be exhibited by rounded crest and 

 hollow, the crest being as much above the middle line 

 as the hollow is below. Apart 

 from such simple forms, waves 

 may be of many shapes, high 

 and sharp, flat and broad, and 

 so on. Now it has been shown 

 that every compound wave is 

 capable of being resolved into 

 simple waves. Fig. 187 shows 

 three waves, whose vibrations 

 are as 1 : 2 : 3. The 



blending of these three simple 

 waves produces the compound 

 form marked 4. The form of 

 the complex wave is obtained 

 by drawing a series of vertical Fig. 187. Compound 

 lines. The position of the com- ^aves. 



pound wave at any one of these lines is marked 

 by taking the algebraic sum of the distances of 

 the three simple waves above or below the line of 

 rest, and in that vertical line. Thus, take the ver- 

 tical line a'b', the position of a point of the com- 

 pound wave in this line is obtained by taking the 

 distance in the same line between a' and a 2 , the 

 distance between a 3 and a 4 , and between a 5 and a 6 , and 

 taking their algebraical sum. They are all above the 



