A specialization of music that first appeared in the United States in the mid-1940s, rhythm and blues was an important precursor of both rock 'n roll and soul music. Early R&B was itself influenced by blues music and by big-band and swing-era jazz music. Initially often known as 'jump blues' to its fans, R&B was commonly referred to in the mainstream (i.e. white, middle-class) culture as 'race' music, due to the fact that almost all of its performers were African Americans. Compared to straight Blues, with which it shares chord structures, riffs, and lyrical themes, R&B tends to be louder and faster, uses more electrical instruments, and is often horn-driven. Influential practitioners of R&B include Louis Jordan, Big Joe Turner, Ruth Brown, Ike Turner, Big Mama Thornton, Screamin' Jay Hawkins, and Ray Charles.