Good voice acting can’t save a bad game, but talented actors can imbue a game script with genuine emotional freight. Some of the best in-game voice work is not the long bits of dialogue in boring cut-scenes, but tiny, subtle bits of atmosphere. In Tomb Raider, Lara Croft’s quiet, voluptuous moans as she hurled herself off ledges were half of what made the character so erotically charged. In Super Mario 64, Charles Martinet?a longtime voice actor who has done dozens of Nintendo titles?does almost nothing but grunt, sigh, giggle, and gasp, yet he gives the tiny anime plumber a surprisingly human quality. —Clive Thompson
—The Game’s the Thing: Why are Hollywood actors starring on your PlayStation? (Slate)
The article actually focuses more on A-list actors who are starting to appear in videogames, but I found this section on non-verbal vocalizations interesting.