Apollo Justice: Ace Attorney's title protagonist is notable in-universe for his loud voice. Kinda lampshaded in Case 1, where he mentions his daily "Chords of Steel" training. And during his first trial the judge actually calls him out for yelling in court. To be honest, every lawyer in Ace Attorney has some pretty epic OBJECTION shouts, but Apollo is the king of them all.
And from the first game, Officer Mike Meekins, who sometimes SHOUTS INTO HIS MEGAPHONE TO GET HIS POINT ACROSS with accompanying "feedback" sound effect. When we see him without the megaphone in Investigations he's a little more subdued.
Hugh O'Connor: Then again, we're not like you people, talking endlessly in those annoyingly loud voices.
Athena Cykes:OBJECTION! Annoyingly loud voices? I'd like it if you refrained from insulting my partner like that!
Apollo: Normally, I'd shout, "Objection!" right about now, but I'll take this one for the team.
In the same game, the suspect Robin Newman apparently screams even louder than Apollo most of the time. That is, until her true gender is revealed.
Athena Cykes to an extent too, she's happy to make noise be it with her mouth, blowing a animal trainer whistle (shown if you show her said whistle in the DLC case of Dual Destinies), or slamming her desk as hard as she can. She even voice trains with Apollo as shown by the Prologue anime of Spirit of Justice.
Misha of Katawa Shoujo. Generally seen translating for the deaf-mute Shizune (to and from sign language, in case you were wondering). The game's set in a school for the disabled, so some fans think Misha's partially deaf.
Shizune's father Jigoro also has a tendency to speak very loudly, but this is simply because he is rude and seemingly in a perpetual bad mood. Things get humorous when he gets into an argument (read:epic shouting match) with Misha. Shizune and Hisao take the opportunity to bail out and disappear together.