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LXI. Researches in Acoustic*. 

 By Alfred M. Mayer*.— No. VIII. 



[Continued from 4th Series, vol. xlix. p. 432.] 

 Contents. 



1. On the Obliteration of the Sensation of one Sound by the simultaneous 



action on the ear of another more intense and lower sound. 



2. On the Discovery of the Fact that a Sound, even when intense, cannot 



obliterate the Sensation of another Sound lower than it in pitch. 



3. On a proposed Change in the usual Method of conducting Orchestral 



Music, indicated by the above discoveries. 



4. Applications of the Interferences of Sonorous Sensations to Determi- 



nations of the Relative Intensities of Sounds. 



THIS communication is preliminary to an elaborate paper 

 on the above subjects. For conciseness and clearness 

 I present trie few facts I have now to offer in the form of 

 notes of experiments. 



1. On the Obliteration of the Sensation of one Sound by the 



simultaneous action on the ear of another more intense and 



lower sound. 



Experimental Observations on the Obliteration of one Sound 

 by another. — Several feet from the ear I placed one of those 

 loud-ticking spring-balance American clocks which make 

 four beats in a second. Then I brought quite close to my 

 ear a watch (made by Lange, of Dresden) ticking five times 

 in the second. In this position I heard all the ticks of the 

 watch, even those which coincided with every fourth tick of 

 the clock. Let us call the fifth tick of the watch which co- 

 incided with one of the ticks of the clock, its fifth tick. I 

 now gradually removed the watch from the ear and perceived 

 that the fifth tick became fainter and fainter, till at a certain 

 distance it entirely vanished and was, so to speak, " stamped 

 out " of the watch f. 



Similar and more striking experiments were made with an 



* Communicated by the Author. 



t In the publication of this paper in l Nature,' Aug. 10, 1876, rny 

 friend Mr. Alexander J. Ellis, F.Ii.S.. appends the following note to the 

 above experiment: — "The precise numbers of ticks in a second here 

 mentioned are not necessary for roughly observing and understanding 

 these phenomena. I observed them by a common American pendulum- 

 clock placed on a table (which increased the power of its half-second 

 ticks), and a watch beating five times in two seconds. The Rev. Mr. 

 Haweis informs me that he has often noticed a similar effect at night 

 with ordinary watches. The sensation produced by the obliteration of 

 the tick when the proper distance of tne watch from the ear has been 

 attained, and the consequent sudden division of the ticks into periods 

 separated by silences, is very peculiar. It is difficult not to believe that 

 some accident has suddenly interfered with the action of the watch 

 instead of merely with our own sensations." — A. J. E. 



