The Theory of Binaural Audition. 261 



copper rod connected with the experimental rod, so that obser- 

 vations of temperature may be taken in the hotter as well as 

 in the cooler portions of the rod. 



Errata in No. 42 (March 1879). 



2Va v ° 



Page 207, equation after eq. (6), for n Qga y read |P« C0 (log a) 2 . 



— 209, eq. (8'), for 247 read 274. 

 Mr. Stocker, Physical Demonstrator in the Clarendon Laboratory, 

 Oxford, has been good enough to point out to me, in addition to the above 

 errata, that the value of log a is more nearly "0077 than '0076, as I have 

 taken it, and that twice the reciprocal of this number, which in equation 

 (7) is called 267, is more nearly equal to 260. 



XLII. The Theory of Binaural Audition. A Contribution to 

 the Theory of Sound. By Anton Steinhauser. 

 [Concluded from p. 197.] 

 6. rjlHE results developed in the preceding theory, how- 

 J- ever, may be influenced by many circumstances — as, 

 for example, by the conduction of sound through the earth or 

 through the body, and particularly by the effect of reflexion. 

 For if, in addition to the direct rays which produce the inten- 

 sity i t in one ear and i 2 in the other, there reach the ear other 

 indirect rays by reflexion from the ground, or walls &c, then 

 the intensities with which the sound is perceived in the two 

 ears become respectively (^ + p x ) and (i 2 + p 2 ), where the in- 

 crements of intensity p x and p 2 may evidently be to one another 

 in any ratio whatever, according to the existing circumstances. 

 Then from equation (2) we get 



Oi + PiHOs + Pa) 

 or 



tan« = / ft ~^ + ^"^ tan/3. ... (3) 



Consequently the angle a is another one than that indicated 

 either by the real direction of the source of sound, or by the 

 projection of the direction of the sound-rays upon the plane of 

 best hearing. 



The angle at which we estimate according to the sensations 

 the position of the source of sound (regarded no longer as ne- 

 cessarily in the plane of best hearing) approaches the more 

 nearly to the angle at which it is actually situated in propor- 

 tion as p x and p 2 are simultaneously diminished, and coincides 

 with it when p 1 = p 2 = 0. This is almost attained in the case 

 of weak sounds; for then the effects of reflexion, usually still 

 weaker, are scarcely or not at all perceived. 



