Penetrating convoy screens, and one bug/technical question

[andqui]

1) I'm having the wind/wave sound bug where it continually loops, even while submerged or in calm weather, occuring after I alt+tab. Most of the references to this known bug I can find are from several years ago- is there a known fix for it nowadays?

2) I need help getting past convoy escorts (NYGM). I'm having an issue with escort vessels seemingly detecting me magically when I try to approach submerged under the convoy screen. I'm guessing that they are constantly pinging for contacts while making their sweeps, so I should try to avoid passing near them or at too shallow a depth.

However, there have been several times where I have made my approach, not heard any pings, only to find the convoy alerted and buzzing with activity even before I raise my scope. How on earth do they detect me? I'm not going very fast under water, and besides hydrophone ability should be reduced with them constantly moving around at 7-10 knots up there.

thanks