Speaker Box is a species that include sentient speaker boxes. They come in many variations and shapes, but the most notably being the Announcer. They apparently are revealed to have their own "home", which through the Announcer's diary, is possibly from outer space.
Thanks to Announcer's diary, other things about the Speaker Boxes are known. Apparently, they can't be on Earth without a built-in Earth attraction unit that keep them pulled to the Earth's core, if not, they will get sucked out of Earth, and back to space. However, the Speaker Boxes need to pay the costs to maintain it. As with each vibration from their speaker driver, attraction and repulsion duke it out, repeated until the first one diminishes.
- The "home" said above is most likely the spaceship most of the other Speaker Boxes in the show were seen, again, based of what the Announcer wrote in his diary.