Abstracts of Technical Papers ' 



Carrier Trii-phony on Pimrr fJurs.' N. 11. Si..\r(,ii iiu .iii<l \\ . \'. 

 W'oi.Ki;. Tlu' liii)(lain(.-ntal n-iiiiiri-iiH-nls of a tck-phoiR- tirruii an- 

 oiitliiud brioHv- and translated into the terms of the jM)\ver line carrier 

 telephone problem. Considerable data on transmission line rhar- 

 acteristics at carrier frequencies are presented, which clearly show 

 the maRnitude of the transmission problem and the best frequency 

 values to employ. The advantages of using the "metallic circuit" 

 arrangement rather than the commonly emplo\ed "ground ri'turn" 

 arrangement are emphasized. 



One of the chief problems in carrier tele[)h()n>' on jjowcr liiu's i> to 

 provide an efficient means of connecting the carrier equipiiu'iit to the 

 power line, and the various possiiiilitics .md preferred imtlKid-- .ire 

 discussed at some length. 



The nature of the circuits and eciuipmeiit eni|)lo\ed are then de- 

 scribed, together with an indication of their range of usefulness in 

 power line telephone communication. 



The Xatiire of Laiif^uaf^e.' R. L. Jom-.s. In iiilnHluclimi. the liis- 

 tory of human language is outlined and the manner of speech ])ro- 

 duction is briefly described with special reference to English. Following 

 this is a summary treatment of available data on the subject of speech 

 and hearing. Much of this is the result of investigations carried out 

 during the past few years in the Research Laboratories of the Amer- 

 ican Telephone and Telegraph Company and the Western Klectric 

 Company, at New York. 



Human speech employs frequencies from a little below 100 (Acles 

 per second to above G.tXHJ cycles, a range of about six octa\es. The 

 ear can perceive sound waves ranging in pressure amplitude from 

 less than 0.001 of a dyne to over 1 .000 (Kius .md in frequency of 

 vibration from about 20 cycles per >((iiii(l to .ilioui JO, 000, a range 

 (}f about ten octaves. 



The intensities and frequencies used m(»t in conversation are ihoM- 

 ItKated in the central part of the area of audition. The energy of 

 speech is carried largely by frequencies below 1,000, but the charac- 

 teristics which make it intelligible, are carried largely by frequencies 

 above 1,000. I'nder quiet conflitions gcKxl understanding is possi- 



' The purpose of these abstracts is to supplement the contents of the Journal 

 by reviewing papers from Bell System sources which relate directly to electrical 

 communication but which will not be reprinted in the Jnurnnl. 



•Journal .A. I. K. E., Vol. XI. Ill, p. .177, .Apr., 1924. 



' Journal .A. I. E. E., Vol. XI. Ill, p. M\, .\pr., 1<>24. 



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