This excerpt from Critical Survey of Poetry sheds light upon your meaning of poetic voice, or the voice of the poet, and therefore, upon the answer to your question:
While Jones changed his name to Amiri Baraka and radically altered his poetic voice, Brooks accommodated her new insights to her previously established style.
In the beginning of her career as a poet, Brooks adopted a traditional style of poetic form. It was through the resulting poetic voice that she expressed her poetry, which won the Pulitzer Prize in 1950 for Annie Allen, her second volume of poetry that was published in 1949. With the dawn of the 1960s militant African American anti-racism movement, Brooks experienced a shift in vision, specifically as a result of a 1967 conference at Fisk University. From then on out, though Brooks still insisted upon her established style, with elevated language and traditional form, Brooks' poetic voice altered to reflect her new vision of poetry directed wholly toward an African American audience.