Paah

Many musical tracks in the New Super Mario Bros. series incorporate a form of, mostly in the form of "bah" vocals. Interspersed within a level's music track, these sounds, when heard, cause objects and enemies on-screen to perform a brief action simultaneously.

New Super Mario Bros.
New Super Mario Bros. is the first game to have a function for the "bah" sound. In the main theme, underground theme, athletic theme, and underground theme, a "bah" sound plays which some enemies and objects will react to in their respective levels. A table summarizing entities' responses across different New Super Mario Bros. games can be found below.

In certain level types, "bah" vocals are superseded by other sounds with the same function: in New Super Mario Bros., the underwater music uses a brief tinkling effect for the same purpose.

New Super Mario Bros. Wii
While New Super Mario Bros. Wii uses new overworld, underground, and athletic themes, the "bah" sound reappears in these new versions, serving the same purpose. It also appears in the brand-new desert, beach, forest, snow, and lava overworld music, as well as the lava underground music. This game marks the start of enemies in tower levels reacting to the music, as the tower theme uses a percussive sound to the same effect as the "bah".

New Super Mario Bros. 2
In New Super Mario Bros. 2, the "bah" sound reappears in the new ground theme and athletic theme, as well as the desert, beach, forest, snow, lava overworld, and lava underground music reused from New Super Mario Bros. Wii. Additionally, it is the only game in the series to incorporate "bah" vocals in the music of Ghost House, tower and castle levels.

Accompanying the ground and athletic themes are additional "yah" sounds, which play alongside the melody in the overworld theme and instead of it in the athletic theme. As these songs are otherwise the same as their New Super Mario Bros. Wii counterparts, enemies and objects only react to the "bah"'s present in their original versions.

New Super Mario Bros. U
In New Super Mario Bros. U and its port, New Super Mario Bros. U Deluxe, the "bah" sounds reappear in the underground, underwater, desert, forest and snow overworld music from New Super Mario Bros. Wii. Additionally, they are present in the new overworld and athletic themes. New Super Luigi U, an expansion to this game, simply reuses the music from New Super Mario Bros. U, so the same actions occur when the "bah" sound is played.

Super Mario Maker series
The Super Mario Maker games reuse the underground, underwater, desert, forest and snow overworld music from New Super Mario Bros. Wii, and the overworld and athletic music from New Super Mario Bros. U. However, enemies in these games do not react to the music, so the "bah" sounds serve no functional purpose.

Table of reactions
The table below lists the reactions of various elements in the New Super Mario Bros. games to these sounds. Many of these reactions are aesthetic, but a few of them can have a small effect on gameplay.