growling vocals are talentless garbage, plain and simple
no one knows what white trash is and should stop using this boundry to stereo type rural whites who are perhaps as much if not more diverse than burbies and urbanites, trash exists in all races, generally of greater percentage in non whites, end of that story.
Im to old to directly answer the OP question, both parents being gone, my mother in 1970, but my father did take us to see Chicago and Jesus Christ Superstar in the summer of 70 or 71. Granted both had cross sectional appeal but both also had a large influence on my future taste in music. He did however not like my hardrock, naturally and refered to all the vocals as screaming which was accurate, Robert Plant, Getty Lee, Steve Marriot, Ian Gillan all screamers that I should point out used actual scale tones and applied rhythmic melody but yes indeed screamed out their parts.
On a related side note I would like to point out that I truely believe Jesus Christ Superstars origional studio recording represents Ian Gillans strongest vocal examples and they could not have picked a better vocalist for the job, he never toured with the show though. Murray Head was also amazing as Judas, the remaining cast of vocalist set off a excellent contrast with greatly varied voices and tones. In the world of more recent progressive music, Paul O'Neill associated with Savatages later more progressive and concept albums as well as Transiberian Orchestra was once the touring guitar player for JCS. The opening guitar solo/intro may have been one of the first examples of recorded dark and dissonant guitar sounds that later became popular in metal.