Since the sons of Atilla enemies in the game are nearly silent and you can hear allies over 2km away through 2 mountains.
Bombs are also exceptionally loud, while roket and HE explosions are extremely quiet in comparison. Even if a bomb weighing 100kg explodes 1km away, it is louder than an 80kg missile warhead going off 5 meters from you.
Gajin said we would get the option to set different volume levels for allied and enemy engines (vehicles) with Sons of Atilla, yet we still do not have that feature, and we still have this absurd bug.
Sound in WT is probably the most important feature, at least for ground RB and Sim. Yet it has never worked properly, and bugs go ignored for months or years.
It seems to me like Gajin implemented the feature but forgot to add the menu option. And the option we have now is for allies only, while enemies are set to a permanent minimum.