Nictalope, I went through your mod just before starting on mine

. The sounds are very good for the standard SH3 surface sounds. I did go through the US Sonar User Manual that explained all the knobs and the procedures, a very interesting read. It just reminded me what could be achieved if we were allowed to script the game ourselves.
As it stands, depth doesn't have any change on sounds in the game. As soon as you hit the surface, the sounds start. This annoyed me terribly when traveling thorugh storms and the waves smashed into the hydros whithout causing sound. Speed also has no effect on any sound. Only your engines raise the volume (and pitch) of the sub sound. In other words, moving water around the hydro doesn't make any sound. Going at 8 knots flank then cutting the engines will instantly cut the noise, which may or may not be realistic. Maybe SH5 will adress these issues and implement each knob and phisical effect and save the world from hunger, bring peace and make women feminine again...
But until then, this mod does what it's supposed to, make you rely more on your watch crew and be more forgiving to your soundman. If you can find any sound samples from real german subs, I'd be very very interested in having them in SH

.