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by jcrawfordor
1074 days ago
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> I read somewhere once that a sensor, sonar or hydrophone, in UK waters could detect the sounds come from a New York harbour, which gives an insight into the distance sounds can travel underwater, but considering all the noises that can be detected, having sound processing abilities, a little bit better than something like Dolby Noise Reduction, is the key part of the underwater arms race. I didn't really get into this in the article but there's a phenomenon called SOFAR (I think this does stand for something but the acronym is sort of a joke). It's basically a specific static water pressure (and thus depth) in which sound "ducts" sort of like how HF radio can duct in the ionosphere. As I understand it, it's not at all unreasonable for a sound in the SOFAR channel to go clear around the world. I know there are cases where hydrophones have recorded a particularly loud sound multiple times because of it coming "the long way around" as well as echo effects. Some of these sounds have been things like "perhaps the loudest sound ever produced" and are attributed to seismic phenomenon, but there are a lot of strange things going on in the ocean and hydrophones continue to provide plenty of questions for marine researchers to answer. And, of course, at least some of the IUSS sensors are very intentionally placed within the SOFAR channel to capitalize on this effect. |
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https://en.wikipedia.org/wiki/SOFAR_channel