Clefairy and Clefable are Fairy-Type Pokémon (formerly Normal-types). They are shy and timid Pokémon. They do not like fighting and prefer to live in quiet areas, so I would expect to have a high and sort of quiet voice. But also playful sounding at the same time. Clefairy would sometimes speak in 3rd person, and Clefable no longer have the 3rd person way of speaking, and would speak in a more mature sounding voice than Clefairy.