FWIW, I have heard "cavitation" noises in my sub while drifting at periscope depth. Not sure if they are erroneous program noises that only I can hear, or if they reflect some flex in the sub at such a shallow depth due to heavy surface seas (it was choppy upstairs, but not raining). No destroyer homed in on me, but I was well away from the convoy when it happened so I don't know if they could hear it or not. Won't make a difference if you are being actively pinged, but might if a destroyer is drifting nearby while you try to slip by.
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