Those big square egg cartons have been used to tame the acoustics of garages by, yes, garage bands at least as far back as the mid-60's, when every suburban block in San Jose/Cupertino (and the rest of the South Bay) had a band practicing after high school got out for the day. Pictures suggest it was the same all over the U.S.A.
Pro studios back then (before diffusers were developed) often had the walls of their control rooms covered in that white porous material with little holes drilled into it, like that I saw in school classroom ceilings.