This trophy is titled "
In A Different Key" and it requires you to set an alternate voice greeting for a character in a player match.
So, from the Main Menu, select Network and then choose Lobby.
Once in a lobby, press the
Button and choose Player Match from the Lobby Menu. You'll now be in the Create Room Menu where you should now press the
Button to create your Player Match. You'll have another option for room accessibility and you can choose whatever option.
With the Player Match Lobby now open, press the
Trigger to open the Chat Menu. Scroll down to In Character and choose a phrase with the
Button. The phrase will be played in the lobby and you'll unlock the trophy.