Level 5-5 is the shortest tune in Super Noah's Ark 3D and is only played in a single spot in the game, Level 5-5. The song is the same for both the DOS and SNES releases, but the different audio hardware plays them each with a distinct sound.
Super Noah's Ark 3D (SNES)
Level 5-5 tune is along the rarest because this is only used in Level 5-5 (the other one is Level 6-1).
The song is output to S-SMP chip.
Super Noah's Ark 3D (DOS)
In the DOS version, Level 5-5 is used in the same level as in the SNES version and is the only one-time song in the game.