Typically if I'm playing someone I don't know I just keep quiet. It helps everyone concentrate. Although if something extraordinary happens like a clutch tech, hard read, or stage jank (looking at you lylat) I will probably laugh about it a bit or say something about it.
If I'm playing someone I know, however, I often am pretty vocal in the match. If I take a hard hit I exclaim "GAH!" or something of the sort, If I live the hard hit, I say "we livin'!", and if someone makes a mistake I laugh about it, and other stuff like that. I still try my best to win but I don't have to be afraid that the person will be offended or angry at me. Nothing distracting just fun interactions. And of course I pop off if I win a game I had no business winning, or absolutely style on my opponent.
In casual play I am probably the loudest person in the venue. I say "falcon kick!" or "backslash!", or any vocal outbursts that the chacter I am playing says when I execute certain moves, I announce the combos I'm doing as I do them, such as "ding, dong" when doing DK cargo throw stuff, or "here comes the zero to death" when I start a combo as Bayonetta (disclaimer: I have never actually gotten a zero to death with Bayo).
Basically in tournament play, I don't see any reason why not to talk a bit, although make sure you respect your opponent(s) and if they want you to be quiet, respect that. Being completely stoic to your opponents doesn't leave as good as an impression, and some friendly chatter between matches is great. For the great majority of us, this is all for fun anyways since we probably aren't earning any money off these tournaments, so do whatever you need to do in order to have more fun!