PPCHalt

PPCHalt is a function that's called when a Wii or Wii U system crashes. This could be due to many reasons. When this happens, the system suddenly freezes on the last frame and loops the last bit of sound, making an annoying solid tone noise that can be loud depending on the frame. A PPCHalt doesn't happen often with regular vanilla gameplay and is more likely to happen if you use game modifications.

2 games that this happens on often are Super Smash Bros. (Brawl and Wii U) and Minecraft (Wii U). The former especially happens when using one of the many mods that are available for the game.