Asphalt and Ablution
From Halopedia, the Halo wiki
<youtube width="300" height="300">0J9PYw1mxDA</youtube> Asphalt and Ablution is a track from the Halo 3: ODST Original Soundtrack.[1] It contains the tracks Still Grounded, Island of War, Hardboiled, and Sneaking Suspicion.
Ablution, in many faiths, means ritual purification, a reference to how the Covenant see the Humans as heretics and seek to open their eyes to the Great Journey.
The track plays on the Main Menu randomly.