Anyone know the singer for the Klingon portion of 'We Are One'?

I know that the utterly incomparable Bruce Horak came back not as Hemmer but as the Klingon for this episode. However the singer, was that Bruce too? If so then I’m genuinely shocked. I thought for sure that it was Weird Al. It sounds almost identical. If it’s not Weird Al himself then it’s a pitch perfect double....