kijangnim, I presume you are an authority on the attenuation of sound underwater? Would you care to tell us some more about hearing it from WELL below that 1000' level? What about interference patterns? What about simple square law signal attenuation with distance? What about non-linear properties of water? What about its dissipative characteristics for sound waves at the pinger's frequency? Please, do tell us more about what supports your bald assertion. I'm ready to read.
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