The reason we could hear all of the Jedi voices in TROS is because Qui-Gon’s been piecing them back together since Order 66 happened.
While he was chatting with Obi-Wan on Tatooine, he was sitting in the metaphorical clover field of the Cosmic Force, patiently picking through it for all the little bits of Mace Windu’s soul, so he could hear his friend sigh with exasperation at him for the rest of eternity. He collected the scattered pieces of Ayla’s soul like eggs in a basket, remembering the way she giggled as Quinlan gave her piggyback rides through the Temple. He used one of those blueberry picking filter things to find Kanan Jarrus, because he had people to watch over.
It was slow going, but it was worth it for his family, to hear them again. And when Obi-Wan and Yoda died, they joined him in his work. That’s why we can hear them. Ki-Adi, Adi, Depa, Luminara, Plo, Kit, Agen, all of them. Qui-Gon. Clover patch. Blueberry picking. Egg hunting.
Awww, I love this.