im a step further.
Seems like ive changed something else before. Item2 here must be the hydrophone. Setting MaxSensorHeight to -5 makes you hear sound only submerged.
Thats good but not exact what i wanted. The other Items do not change anything. Maxrange also only effects the crew yelling when they grab a contact. Setting it to 5000 makes your crew find that contact at that range. You can still hear it however loud and clear at 20000 and above

. So looks like there is no way to make it work realistic. We can either have full functional hydrophone on surface or not.
But maybe someones got an idea lets see.