ELECTRO-MAGNETIC TR/iaSDUCER 



In order to fill in an untested part of the range at the lower 

 frequencies, the Bell Telephone manufactured transducer (lK-2) shovm 

 in Figure 28 was set up in the pond at Leetown„ The sound frequencies 

 it was capable of producing (200 to 10,000 cps) overlapped the range 

 of the electro -magnetic water hammer tested in 19li7 (67 to 3,000 cpso). 



The familiar hum of the sine curve wave of sound could be heard 

 by everyone, up to about 9^000 cpSo Above that frequency the sound 

 escaping from the vjater was not audible to most listeners due to the 

 lack of intensity. The trout did not respond to any sound frequency 

 within the range of the Bell transducer^ The tests ^^^ere carried out 

 in conformity with previous runs with other equipment and the results 

 are shown in Figures 26 and 27„ The instrument was suspended at a 

 ■distance of 2 feet from the fish in section no. 1, and with the dia- 

 phragm 2 feet below the surface. Contingency tests again showed sig- 

 nificant differences in distributions of fish of sound tests and con- 

 trols, but, as before, there is nothing to indicate that the sound 

 stimulus was responsible. 



Except for casual tests with detonating caps, the sound work with 

 the U. S.Navy was concluded. In a test of the effect of small explo- 

 sions upon trout, sumberged fulminate of mercury detonators xirere touched 

 off in succession at regular intervals of one to two seconds. As 

 before, the fish "started" at only the first blast and did not swim 

 away as the explosions continued. 



SUMMARY AND CONCLUSIONS 



lo Guiding fishes by means of sound generating equipment 

 Installed at dams and diversions would be desirable because of its 

 freedom from physical floating equipment and ease of maintenance. 



2. Fishes have been conditioned to respond to sound as a signal 

 food, but 

 questionable, 



for food, but the evidence of attraction to sound alone is rare and 



3o Certain fishes maj'' be frightened momentarily by any noise but 

 adjust to disregard it (become conditioned) almost instantaneously. 



lio The four sound propagating pieces of equipment tested at 

 Leetown, West Virginia are described as follows; 



(a) "Water Hammer" = electro=magnetic transducer producing 

 sine curve sound ranging from 67 to 3,000 cycles per second. 



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