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US1796774A
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Multiple-control switch
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Multiple control switch
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Submarine signaling apparatus
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Method for finding the direction of sound
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Sound-receiving device for submarine signaling
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Apparatus for finding the direction of sound
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Diaphragm for the reception and conversion of sound waves
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Apparatus for finding direction
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Microphone
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Microphone
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Signal receiving system
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Visual and aural determination of direction and distance of sound
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