I don't know this is the right section - if not please move.

It makes gangs of sense to make shooting quieter - in the military, maybe you could more easily hear what your commander is telling you, or what the enemy is up to. For the rest of us, reduced risk of hearing damage and better communication with fellow shooters while shooting are big pluses.

Going the other direction though - and this is my question - would there ever be a reason to try to make a firearm sound louder? Say in military use for making it seem your side had more people and/or different firearms than you really do have, or as a signaling device, or just for grins?

If so, are there ways that is done?

An interesting question.
I cannot answer it directly, but it reminds me of something I have long wondered about.

Back when the 357 Magnum cartridge was widely recognized as the best threat-neutralizing handgun round, the Federal 125 grain Classic load also had the best reputation for the purpose. That was probably because although none of those loads’ velocities were what the manufacturers claimed, it was pretty hot, it had a large exposed lead nose with massive hollow point, and it expanded readily and reliably. It also had the reputation of producing one of the most impressive muzzle blasts of that group of cartridges.

The pundits will claim to believe that something like muzzle flash and noise can have no effect on the “stopping power” of a cartridge other than psychological, but whatever convinces an adversary to stop being a threat, whether it’s physical or psychological, is fine with me. It’s true that we cannot and should not rely on psychological effects to save us from deadly threats, but when it occurs, why would we discount it? That isn’t intended to suggest that we should try to deliberately enhance the psychological effects of our gunfire, but as the expression goes, could it hurt?*

* I don’t know, but I will point out that LTC Dave Grossman who has written extensively about killing and military combat evidently believes/believed that it was important. He opined that the reason early firearms were adopted in favor of bows and arrows was precisely because of the psychological effect of their smoke and muzzle flash. I believe that Grossman holds a number of crackpot ideas, not least that one, but it does demonstrate that we’re not the only ones to believe the idea is worth pondering.

Sometimes when I shoot next to someone with a certain brake it feels like my eyeballs are going to pop out of my head..

I know people hate it during classes when I use my duty gun (Glock 31).

Sledge Hammer did invent the Loudener way back in the day.