From Halopedia, the Halo wiki
This article is about the soundtrack. For the Orbital Drop Shock Trooper, see Rookie.
The Rookie is the second track (Disc 1 Track 2) included in Halo 3: ODST Original Soundtrack. It is composed of Strong Silent Type (0:00-3:08), Postpartum (3:08-4:59), and Proceed with Caution (4:59-7:27).
Strong Silent Type
Strong Silent Type (3:08) begins with low strings playing in ambiance. Muted percussion enters in a slow rhythm. Low strings transition to a flowing melody with single piano notes in accompaniment. The piano notes play in a short notes until heavy percussion enters slowly building up tension. With a cymbal clash, strings enter with a trembling melody before fading into the background melody. Winds take over in an echo of the trembling melody, followed by the percussion and low strings slowly build up and swell to a minor key. The piece ends with a high-pitched chord. This piece plays throughout the Halo 3: ODST campaign level Prepare To Drop. The trembling melody is incorporated into Street Sweeper (from the later track Traffic Jam), Mercy Plea (from the later track Special Delivery), and Orbital Drop Shock Trooper (from the later track Finale).
Postpartum (1:51) begins with digital notes playing in a minor key. The electric guitar joins in often playing three notes with reverb. Strings enter and lead into the next piece. This piece plays in the campaign level Mombasa Streets, when the Rookie first wakes up and contacts the Superintendent.
Proceed with Caution
Proceed with Caution (2:28) features rhythmic muted percussion and muted low strings playing the melody from Strong Silent Type. The percussion takes over for a short section before the low strings returns louder with the melody. The percussion takes over again before high strings fade in for a finish. The piece plays in the campaign level Mombasa Streets, when Rookie enters the building in Sector 5 overlooking Tayari Plaza.