This not a question, but something I wanted to add here for reference looking for it, as I thought it possibly occurred in Season 11 and would come up sooner than later on the 24/7 channel. Using all available YouTube episodes from Season 11 through to the 8/25 episode or the next to last show of the year, and then viewing back the opening to the Season 12 premiere as well the following week, it stands to reason that said premiere was the debut of the higher pitched version of the classic theme that would come to mark the rest of the show's run under Barker's watch. So if anyone was curious about that or wanted to make a note of it in the FAQ for posterity, there you go.
I thought maybe it got changed mid-season somewhere and pinpointing the transition woulda been tougher, but..makes more sense it woulda changed right at start of Season 12 instead.