s 4 



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 differ- 

 Conditions more ence tones in a Psychological laboratory. 

 or less favorable ^ ' s Qtiite 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- 



tones 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- 

 tion of a lower and a higher tone the latter 

 is sometimes entirely inaudible, provided, 

 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 hardlv been 

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

 easily observed with such ratios at 1:2, •-'::'>, or 1:3. Let us 

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

 point of view. 



The dis- 

 appearance of 

 a higher tone 



Fig. 26. The combination 1 and 2, unequal amplitude* 



