Blindlight
From Halopedia, the Halo wiki
Blindlight Media is an American sound company. They tote themselves as "a Hollywood production resource for the video game community." They use acting talent to produce high-quality voice-over production for video games.
They are responsible for the sound and voice-over production of Halo 2. It is likely that they hired many of the voice-actors and actresses who participated in the making of the game.
