Hehe, nice.
I have another thing:
If you play title 5 from the Halo2 OST Volume 2 (Mausoleum Suite - 1. Destroyer's Invocation) backwards (just take the beginning from 22 seconds - 1 minute 20 seconds and play this piece backwards) you hear an english text.
It says for example that time has no end and no start and such things.
Me as not english native speaker don't understand everything because the voice is deformed but maybe you get it.
Seems to be the Gravemind dialoges...