Abstracts of Bell System Technical Papers 



Not Appearing in the Bell System 



Technical Journal 



I'hi- Aiuiitory Maskin;^ of Our Pure lone By Anolber and Us Prob- 

 able Relation to the Dynamics of the Inner Ear.^ R. L. W'ec.ix and 

 (.". K. Lane. The authors iisod an air damped tt'lcphotu' receiver 

 supplicti with variable currents of two frequencies and determined 

 the amount of masking by tones of frequency 200 to 3500 f<jr fre- 

 quencies from 150 to 5000. Except when the frequencies are so 

 close together as to prixlucc beats the maslcing is greatest for tones 

 nearly alike. When the masking tone is loud it masks tones of higher 

 frecpiency Iwttcr than those of frequency lower than itself. If the 

 masking tone is introduced into the opposite car the effect occurs 

 onl\- by virtue of coniiuction through the bones of the head. 



It is shown that combinational tones result when two tones of 

 sufficient intensity are introduced simultaneously, these combina- 

 tional tones being due to a non-linear response of the car. 



A dynamical theory of the cochlea is given which ascribes pitch 

 discrimination to a passing of vibrations along the basilar membrane 

 and a shunting through narrow regions of the membrane at points 

 depending on the frer|uency. This view of the action of the ear 

 offers an explanation of the masking effects. 



Distribution of Radio Waves from Broadcasting Stations over City 

 Districts.- Ralph f^owx and (•. D. ("iILLETT. This is a description 

 and analysis of the results obtained in a radio transmission survey 

 of the cities of New York and Washington, D. C, and contiguous 

 territor\-. Measurements of the field strength of radio signals from 

 stations WC.\P at Washington and WEAK at New York were made 

 at a large number of points. Based on these data, curves are drawn 

 showing how different kintis of territory cause different attenuations 

 and showing radio shatlows caused by mountains and by large masses 

 of steel buildings. In order to visualize the phenomena, the data 

 have also been plottetl on maps, contour lines of ecjual signal strength 

 Ix-ing drawn. These contour maps illustrate graphically the non- 

 uniformity of transmission in city areas and show the nature and 

 extent of the "dead spots" and shadows. 



' Phviical Rnint; II, Vol. XXIII, p. 266, 1024. 



' Presented to the Institute of Radio Engineers, J.miiary 16, l'>24. at N\-« York. 



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