A bassy, ambient humming sound effect of ancient spirits can always br heard in my shanty and three extended rooms after Aporkalypse is ended. I entered the interior of the fifth island to end the Aporkalypse. The ancient spirits were there, and after the Aporkalypse passed away, pig ghosts disappeared. But when I rentered my own house, the sound is still there.
start aporkalypse, see the pig ghosts, then end the apokalypse, the go back to shanty