Music not on the soundtrack

[Philly]

I have noticed recently that there is at least one piece of music that plays in the game, but does not appear on either of the soundtracks. The music in question plays on the 'Delta Halo level', as the first warthog is dropped. It is a heavy drum beat and light vocals, with 'In Amber Clad' resembalences. If anybody can name it in the soundtrack or find it in the map, that would be great.

Just interested,
Phil

[LegendaryModder]

i want it too =D