It was said that Zodiark "rewrote the laws of the star," and that in so doing was able to stop the Sound. It's still unclear what caused it; the only thing really known about the Sound is that its effects were originally localized, small-scale disruptions. When it reached Amaurot it... basically caused the Apocalypse. (Literally. The bosses are identified as "Beasts," as in Beast of Revelation, and the final boss "Therion" uses one of the names attributed to said Beast.)

One thing that worries me with the new info from Shadowbringers is Lahabrea's pre-battle dialogue in the Praetorium, though.

Quote Originally Posted by Lahabrea
The growing imbalance afflicting the planet must be redressed. If it is permitted to worsen, the very laws of existence - both aetheric and physical - will be warped beyond all recognition. Know you the root of this corruption? Hydaelyn! Like a parasite, she must be burned out if the planet is to recover. And naught but the return of the one true god will ensure her complete excision.
Now, I might be crazy, but to me it sounds like he's suggesting that without Zodiark's return the Sound might come back. (Granted this is coming from an Ascian and was written like, what, five, six years ago... but even so...)