 He remains one of the genre's most recognized artists.His lean and powerful style exemplified the Stax sound; he was said to be "the heart and soul of Stax", while artists such as Al Jackson, Dunn and Cropper helped to expand its structure.His open-throated singing, the tremolo/vibrato, the manic, electrifying stage performances and perceived honesty were particular hallmarks, along with the use of interjections (such as "gotta, gotta, gotta"), some of which came from Cooke.