Justin Bieber is a Canadian singer and songwriter who rose to international fame in the late 2000s after being discovered online; his work spans pop, R&B, and electronic-tinged contemporary pop, with later recordings incorporating dance, hip hop, and acoustic influences. Known for a high tenor/ falsetto voice in studio productions and a shift from teen pop to more mature themes, his career has included chart-topping albums and singles and collaborations with a range of pop and urban artists. Mariah Carey is an American singer, songwriter, and producer, active since the late 1980s, widely recognized for her five-octave vocal range, melismatic singing, and songwriting in pop and contemporary R&B, with notable forays into soul and adult contemporary. Carey’s recordings commonly feature lush arrangements, strong emphasis on vocal virtuosity and hook-driven songwriting, and she has been influential in pop and R&B vocal styling.