58 UNIVERSITY OF MISSOURI STUDIES 



If the difference tone results exclusively from the func- 

 tion of the nerve ends located on the last moving section of 

 the partition, its relative intensity is two, according to the 

 above table. But if the difference tone results from the func- 

 tion of the nerve ends of further sections, its relative inten- 

 sity must be higher and the maximum intensity of the mean 

 tone correspondingly lower. That is, the phenomenon of a 

 beating mean tone must be the less pronounced the 

 more audible the difference tone: and the difference tone of 

 a small interval like the one in question must be the more 

 audible the higher the pair of primary tones in the tonal series. 



Summarizing now our interpretations of figure 21, we 

 must say that so far as the meager data reach from which we 

 can draw theoretical conclusions, the fol- 

 The combination lowing seems likely to be the total im- 

 24 and 25: pression (listening with one ear. having 



summary the other ear plugged) : 1. A tone 25 



of the constant, but comparatively weak 

 intensity nine : 2. a tone 24 of the constant, but compar- 

 atively weak intensity twenty-one; 3. a mean tone (perhaps 

 slightly varying in pitch during each period) of an intensity 

 which varies once during each period from zero to a definite 

 maximum intensity and back to zero. This maximum inten- 

 sity may be (under the most favorable conditions) as high 

 as (relatively) three hundred and sixty-eight, but must be 

 much less if the primary tones are above the middle region 

 of the tonal series. Its being less means that the "beats" are 

 less pronounced ; 4. a difference tone the relative inten- 

 sity of which may be (under the most unfavorable condi- 

 tions) as low as two. Its intensity, however, may be greatly 

 increased, at the expense of the maximum intensity of the 

 beating mean tone, in case the pitch of the primary tones is 

 raised. 



