In game it does , and thats what counts , no?
This is an entirely dead end argument. Even if we were to rip the sound from the game file there is still a matter of sound mixing and localization.
The howitzer barrage is accompany by a warning sounds in addition to the smoke. This is by definition not "silent".
Anyone will tell you that relying on smoke alone to dodge off map is not reliable. It's entirely possible for you to miss the initial warning smoke just by looking elsewhere. The sound of howitzer firing It is a perfectly audible sound cue.
And we also have example of On map howitzer in game whose only warning is the sound of firing gun.