Dia: Dia's voice is deep but that only is when she is singing serious/sad songs, but when she is singing happy songs she sounds more to like Hanamaru or maybe a bit like Riko or Kanan! Her voice is very clear and strong! 

Yohane/Yoshiko: Yoshiko's voice is high pitched to medium and not going lower than that because this is meant to be her real voice! It's like Maki's and Nico's voice together as one! (If you can Nico or Maki and mix them together good job!) But unlike Maki when Yoshiko's voice goes up her voice doesn't crack as much, Yoshiko voice can also be a bit childish too! Yohane's voice is very deep going to stand up there with Dia but Dia's voice is still technically deeper. Yohane's voice is powerful and she doesn't need to shout or use alot of power to make people notice her!