While African masks are readily identified, their voices -although essential- are much less well-known: they speak and sing. The most modest masks, intended for entertainment, as well as the most powerful ones with strong supernatural power, use music just as expressively. Since the Dan consider their masks as supernatural beings, neither the spoken nor sung voices of their incarnation can be human. Their wearers must transform their voices into the voices of supernatural beings. The Dan have perfected three techniques to achieve this -they either distort their own voice, alter their vocal timbre by speaking into an instrument, or replace the voice with instruments hidden from the uninitiated. Technically speaking, a person wearing a mask acquires beneath this disguise another personality. According to Black African religious belief, the wearer of a mask abandons his human personality to incarnate a supernatural being, most often an ancestral spirit, a mythical figure or a bush spirit.