.//77./r.//7(>.V f)/' Sl.ll ISIH .11. .Ml.lllons 50 



illustr.iti' till- si^iiit'uMiuv of i1u-m- ideas as an .ii<l in tlu- intcrprclalioti 

 »)f (lata hy ri'foriMire to tlu" ri-sults of our study of the law of rrror of 

 the human car in nu-asurinj; tho i-fhcicncy of transmitters. 



Let us consider the problem of determining the minimum audible 

 soutul intensity. Let us assume that there are ii physiological and 

 psychological causes controlling this sensation measure, and that the 

 probabilitii-s of the causes producing 0, L 2 . . . n elTects are dis- 



SMm iHTZrtsrr 



tributecl normalK-. Because of these differences in luiman ears 

 different amounts of sound energ\- are required to produce niiiiimiim 

 audible sensations. What is the distribution of energies.-' 



The data are given in Fig. fi. These have been previously reported 

 by Fletcher and Wegel of this laboraton>-.'^ The method of making 

 these measurements was described in their original papers. It is 

 sufficient to recall that the results are given in terms of pressures in 

 dynes per square centimeter. Seven hundred and ten observations 

 covering the frequency' range of from (50 to 8,000 cycles are included. 

 The data include results for both ears of 14 women and 20 men, and 

 one ear only for two women and two men. Only ears that had been 

 medically inspected as being physiologically normal were selected. 

 These results, therefore, include variations in the observations of a 

 single observer with those of difTerent observers. 



The natural logarithms of the intensities were added and the 

 average of these was obtained. The distribution of the natural 



"Fletcher, H. and Wegcl, R. L. — I'mcccdings of the National .Xcadcmy of 

 Science— Vol. V'lII, pp. S-6, January, 1922. 

 I'hyskal Kt~i-iiu: Vol. XIX. pp. .i.iO scq. 1922. 



