This DLC contains the following:

In-Game Music (Arranged) - Five Tracks Set

Five arranged tracks will be added to the game.

Track List:

- Confrontation - Allegro 2011
- Confrontation - Presto 2011
- Miles Edgeworth - Objection! 2011
- Pursuit - Uncover the Truth
- Pursuit - Uncover the Truth (No Intro)

Go to the Options menu and under Audio → Soundtrack, select "Arranged" to use these tracks in-game.
You can also listen to them in the Gallery's "Music Collection" section.

More details on the official game page of Ace Attorney Investigations Collection In-Game Music (Arranged) - Five Tracks Set ...