"To a great extent, the powerful emotional mood in Johnson's songs is a result of his masterful manipulation of microtonal intervals in his singing, and in Hellhound, in much of the guitar part. His voice could sound like a moan, whisper, yell, or trombone solo, with seemingly effortless ease — unless he constricted his throat for an even stronger effect — and the slide guitar parts could evoke the same. In a couple of songs, he sings about the wind howling, then the driving guitar rhythm suddenly stops for a moment, while Johnson slides up to a single note that can raise the hair on the back of your neck."

Article from 1998 by Joe Monzo