Many people hold that modern gospel music can be divided into two periods: before and after the Soul Stirrers. The group formed in Texas in the mid-1920s as a close-harmony, jubilee-style vocal group. They gradually expanded their sound into what is now the gospel template, but at the time was still innovative and fresh: lead and backing vocals (rather than four blended voices), guitar accompaniment, some improvised lyrics, falsetto singing (and a wider spectrum of vocal ranges), and a call-and-response pattern that suggested evangelical fervor. By the 1940s, the Soul Stirrers were the premier gospel group in the country, and their reputation only grew when, in the '50s, a young Sam Cooke joined. After Cooke crossed over to secular music, the Soul Stirrers continued to record and perform with a series of excellent lead vocalists, contributing greatly to the creation of modern soul music.