Debiru Boisu (デビル ボイス, Literally Meaning "Devil Voice") is a Fighting Style that is based around the use of Busoshoku Haki and Kami-e . Practitioners would first harden their vocal cords with Busoshoku Haki, to greatly strengthen their voice, this ability is usally used in battle by releasing large, loud and immensely powerful sound waves that effectively annoy, distract and temporarily paralyse any afflicted targets completely, either by screaming or whisteling.