I've heard recently that Brian Johnson of ACDC sings everything in a gritty falsetto. I know this wasn't always the case though. When did he transition from screaming everything in full-voice to singing quietly in falsetto?
His technique and approach really haven't changed in decades. He's still using mixed voice for those highs, and not falsetto. But as you get older, it gets harder to throw much weight into a mix, and the passagio in particular becomes more frail. That's why he doesn't have as much firmness to his highs as he used to. It's a problem a lot of singers who bridge quite early encounter. Axl Rose and Geoff Tate have encountered similar problems in recent years, and Rob Halford has struggled with it on and off for a while (even though Halford bridges a little further up his range than Axl or Geoff). The distortion is just the false cord distortion he's always used. He's just pushing it harder than he used to in order to mask his bridge, and simulate some of the chestiness he can't push into his mix any more. His decline has been fairly gradual, and overall Johnson doesn't sound too bad for his age imo.
He's just using mix super quiet though? I've heard that he sings at a near-whisper volume nowadays. If this is actually the case, I want to know when he adapted to this technique because it seems like he was actually screaming at high volumes for at least the first few ACDC albums he did. Maybe I'm wrong, that's just the impression I have.
He's probably holding back more now than he used to so he can make it through the tours. If he went full force singing those songs at his age, he might be too drained after the first few shows to hit the notes for the rest of the gigs. I'm not really sure quite when the major turning points of his vocal decline would have been, since there are a lot of years I haven't heard performances from. But I haven't seen many really bad clips from Brian (and we have a whole thread of clips like those for different singers lol) so his decline has probably been pretty gradual.