In its earliest form, soul music was a blend of gospel rhythms with secular content. This was around the 1940s and '50s, when icons like Ray Charles and Little Richard were redefining music for all races.
Soul music carries with it a distinctive blend of harsh and gentle rhythms, reminiscent of the blues in the Deep South. Soul music is highly emotional, and the type of rhythms allows soul singers to display that range of emotions in their performances.
Soul music finds its call and response roots in southern gospel and blues songs of the 1930s and early '40s. Repetition is an element commonly found in soul music, particularly where the chorus is concerned.
After World War II, many blacks began to migrate to northern and eastern cities in the United States, including Chicago, Philadelphia and Detroit. With this migration, came the birth of soul music as it's known today.
The late 1960s and early '70s is considered to be the golden era for soul music. Artists such as Marvin Gaye, the Temptations and the O'Jays were popular artists of this era. Record companies such as Stax and Motown played an integral role in delivering soul music to mainstream America.