The use of melisma, a gospel tradition adapted by vocalists Whitney Houston and Mariah Carey would become a cornerstone of contemporary R&B singers beginning in the late 1980s and throughout the 1990s. Hip hop came to influence contemporary R&B later in the 1980s, first through new jack swing and then in a related series of subgenres called hip hop soul and neo soul. Hip hop soul and neo soul developed later, in the 1990s. Typified by the work of Mary J. Blige and R. Kelly, the former is a mixture of contemporary R&B with hip hop beats, while the images and themes of gangsta rap may be present. The latter is a more experimental, edgier, and generally less mainstream combination of 1960s and 1970s-style soul vocals with some hip hop influence, and has earned some mainstream recognition through the work of D'Angelo, Erykah Badu, Alicia Keys, and Lauryn Hill. D'Angelo's critically acclaimed album "Voodoo" (2000) has been recognized by music writers as a masterpiece and the cornerstone of the neo soul genre.