Officers should be able to toggle if they use Loud voice or not.
More often that not marines play pranks and take the megaphone during briefing, for example.
An Officer could then use verb Loud Voice and speak with the big letters of a SL.
In the middle of combat with a CO leading the charge I would pay way more attention to a loud voice rather than a small one.
I know…just grab a megaphone. But SLs dont need those and also most SLs got macros or contact calling and push/retreat orders, Officers would then be able to use those macros as well.