I should also add to that other acoustic factors have a big part now in detection ranges, so now ranges are nearly situation specific to a large degree. Mission designers now have meaningful choices to make about acoustic conditions: SSP, bottom type, mean water depth, region, mean water temperature, time of day, sea state, and season, and cloud cover, to name a few.
Some factors play a bigger role than others in determining sound propagation for any given environment and how shadow zones in particular will form, but mission designers can now customize the acoustic environment to fit the overall theme and tone of their scenarios as they wish.
Think of it as that necessary ambience for a good party.
