Horrifying throbbing low-frequency rumble:
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Energy buildup, Electronic signal
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Electronic signal
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High frequency pulsating electronic signal
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Morse code, SOS signal reception
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White noise
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High frequency signal
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Low frequency pulsing and humming signal
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Location alert, Radar
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Geiger counter
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Transfer, reception, Morse code
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Interference Broadcasting
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Police radio
★★★★★