Title basically says it all. But think about it. The Ethereals heard the Radiant Song, eventually their world was destroyed, and in its wake was Murmur - a being formed of Sound.
If the universe was basically choired into existence by the First Ones, it stands to reason their most powerful creations, the World Souls, would be forged of that sound, and that if one was properly corrupted, twisted, tormented, abused, and neglected, then when it finally burst forth it would do so wailing, not humming.
It would be classic blizzard fashion to just kinda make a random thing they went “hey this would be cool” in TBC into something super important later on
To be fair that’s like half of WoW’s cosmology now.
They got told they had to make an expansion, bought a bunch of peyote and hammered it out in a weekend, and have been trying to justify it all for 18 years.