At least those 2 guys had hearing protectors on their hard hats.
The situation is not quite as extreme as they would have it appear to be. The 130 dB seems to be at the mic located about 6" in front of the speaker stack, not at the listeners' ears. That would be about 94 dB at 32 feet (6 doublings of the distance, 36 dB down from 130), approximately where the listeners were located. That is not abnormally loud for a rock guitar. Also, it is curious that when the box was lowered, the SPL inside did not increase due to the sound that was now reflected back to the source. Massive limp membrane like Acoustiblok does reflect mid and high frequencies fairly well. The box did apparently decrease the SPL at the listeners' ears by over 30 dB so it was below the background SPL, a respectable reduction, but the box was made of 2 layers of Acoustiblok plus an airspace filled with fiberglass insulation, not a single layer of Acoustiblok. Massive limp membranes have been used in this way in acoustics for many years, so this is a useful marketing approach but not as magical as they would have us believe.
