Originally, even though everyone was able to hear Troy through the cube, Evie was the only one whom Troy could hear, as the cube was described to be "genetic." This changes in the first episode of season 2, "Evie's Birthday Wish." At the end of the episode, Evie uses her final wish to request that her mother be able to talk to Troy like she can. As a result, Troy could then hear Donna and they could talk back and forth.