Sound Realm

The Sound Realm is an unofficial realm but theorized to be one of the 4 mystery symbols. Sound Realm: The Sound track is constantly shifting, and enveloped in near-total darkness. Drivers will need to keep their windows down and strain their ears over the roar of their engines to hear the track itself, or else risk slamming head-first into a wall.

Sound Realm Accelecharger "Sound Modulator": This Accelecharger amplifies sounds the driver needs to be aware of while silencing extraneous sounds, thus rendering sound-based hazards ineffective.

Trivia

 * Only one of the 4 Symbols that were shown of the Wheel of Power through out the rest of the Acceleracers Movies.
 * Only one of the 4 symbols that did not get featured in the Acceleracers collectible card game.
 * The Sound Realm was claimed to be the "integral, ∫" shape symbol.