How did call-and-response work between voice and guitar in Mississippi Delta blues?

In Mississippi Delta blues, the call-and-response pattern is a defining feature of the solo performance style, where a singer accompanies themselves on the guitar.12

In this improvised interaction, the singer delivers a vocal line, which is then answered by melodic phrases played on the guitar. This technique allows the instrument to function as a conversational partner to the voice, creating a dynamic dialogue within the music. Musicians often enhance this effect by using a bottleneck or a metal object, such as a knife, to slide along the fingerboard, which allows them to bend notes and mimic the expressive, inflected qualities of the human voice.21

This interplay is frequently supported by the use of vamps—repeated chord progressions that establish the musical foundation before the voice enters—and the overall performance is often characterized by an aggressive attack on the strings that underscores the emotional intensity of the lyrics.2