Here's a complete compilation of everything said by our favorite tentacled boy in Halo 3. This compilation includes quotes that are spoken in the final game, cut dialogue, and the various roaring noises that he makes throughout game, all found in the game's audio files.
Here's a link to where get said files: https://www.sounds-resource.com/xbox_...

NOTE: Please excuse if the Unholy Roars at the end sound somewhat awkward, as I had implemented the the best I could with the way the files were organized.