LOUDNESS 



413 



The second tone calculated is this same hum amplified 30 dl) 

 better illustrates the use of the formula. 



It 



Computations 



The loudness level of the combined tones is only 7 db above the 

 loudness level of the second component. If only one ear is used in 

 listening, the loudness of this tone is one half, corresponding to a 

 loudness level of 70 db. 



Comparison of Observed and Calculated Results on the Loud- 

 ness Levels of Complex Tones 



In order to show the agreement between observed loudness levels 

 and levels calculated by means of the formula developed in the pre- 

 ceding sections, the results of a large number of tests are given here, 

 including those from which the formula was derived. In Tables VII 

 to XIII, the first column shows the frequency range over which the 

 components of the tones were distributed, the figures being the fre- 

 quencies of the first and last components. Several tones having two 

 components were tested, but as the tables indicate, the majority of 

 the tones had ten components. Because of a misunderstanding in the 



TABLE VII 



Two Component Tones (AL = 0) 



