The Fairy Tones are one of the companions of the Cures while they fight to save the world. They all are used to either activate the transformations or attacks. But they also have a mind of their own, ranging from helping the Cures in every day life to even having their own plan to do things. While there are four Fairy Tones in this clip, all of the Fairy Tones will be voiced by the same person as that was how it also happened in the Japanese casting.

Voice type: Medium voice, each Fairy Tone does vary a bit from each other
Reference; https://youtu.be/Y68ochruI_c?t=73