Scorched Earth affects every unit owned by Doom.
Since the buff on them is the same as the buff on Doom, it plays the sound for every buffed unit. This should not happen. The sound should only play on the caster, not on every buffed unit.
The sound can get very loud if you play zoo Doom (dominator, necronomicon, skeleton warriors from devoured troll spells, maybe throw in a manta style and illusion rune). It can get extremely loud when Rubick uses it while having e.g. a Spiderling or Treant army