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BELL SYSTEM TECHNICAL JOURNAL 



TABLE V 

 Comparison of Calculated and Observed Fractional Loudness (Laird, Taylor 



AND Wille) 



Taylor and Wille. ^ As shown in Table V the calculation of the level 

 for one fourth reduction in loudness agrees better with the observed 

 data corresponding to one half reduction in loudness. 



Firestone and Geiger reported some preliminary values which were 

 in closer agreement with those obtained by Parkinson and Ham, but 

 their completed paper has not yet been published. ^° Because of the 

 lack of agreement of observed data of this sort we concluded that it 

 could not be used for influencing the choice of the values of the loud- 

 ness function adopted and shown in Table III. It is to be hoped that 

 more data of this type will be taken until there is a better agreement 

 between observed results of different observers. It should be empha- 

 sized here that changes of the level above threshold corresponding to 

 any fixed increase or decrease in loudness wnll, according to the theory 

 outlined in this paper, depend upon the frequency of the tone when 

 using pure tones, or upon its structure when using complex tones. 



Determination of the Formula for Calculating hk 



Having now determined the function G for all values of L or Lu we 

 can proceed to find methods of calculating hi;. Its value is evidently 

 dependent upon the frequency and intensity of all the other com- 

 ponents present as well as upon the component being considered. 

 For practical computations, simplifying assumptions can be made. In 

 most cases the reduction of bk from unity is principally due to the 

 adjacent component on the side of the lower pitch. This is due to the 

 fact that a tone masks another tone of higher pitch very much more 



^ Laird, Taylor and Wille, "The Apparent Reduction in Loudness," Jottr. Acous. 

 Soc. Am. 3, 393 (1932). 



'" This paper is now available. P. H. Geiger and K. A. Firestone, "The Fstiniation 

 of Fractional Loudness," Jour. Acous. Soc. Am. 5, 25 (l')33). 



