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UNIVERSITY OF MISSOURI STUDIES 



The second of the consequences to be emphasized is 

 probably of little biological significance, but possibly of some 

 importance to the student observing dififer- 

 Conditions more ^"^^ *°"^^ ^" ^. Psychological laboratory. 

 or less favorable ^^ ^^ quite possible that, as a result of the 

 to the observation tapering not being uniform but decreasing 

 of difference as the windows are left behind, the rela- 



*'^'^^ tive intensity of difference tones, which are 



obviously produced by the more distant 

 sections of the partition, is somewhat greater when the abso- 

 lute intensity of the whole sound is rather great. If this is 

 so, it would be advisable to use for the observation of dif- 

 ference tones fairly strong primary tones rather than weak 

 ones. Whether this conclusion is borne out by experience, I 

 must leave to the reader to decide. 



The above discussion of tone intensities naturally leads us 

 to take up the theoretical aspects of the fact frequently ob- 

 served by experimenters that in a combina- 

 The dis- ^ion of a lower and a higher tone the latter 



appearance of is sometimes entirely inaudible, provided, 



a higher tone of course, that it is physically much weaker 



than the former. The reverse, however, 

 that is, the disappearance of a physically weak low tone when 

 sounded together with a strong higher tone, has hardly been 

 observed. The phenomenon in question can, perhaps, be most 

 easily observed with such ratios at 1:2, 2:3, or 1 : .3. Let us 

 study, then, one of these ratios, say 1 : 2, from the theoretical 

 point of view. 



Fig. 26. The combination i and 2, unequal amplitudes 



