Isaacs is singing in a nearly falsetto voice. It just almost on the verge of it. But is just below falsetto. It's like a soft-toned, high register tenor. The tone is incredible. His voice is fabulously unique. He sings "up" in register - has that "held-high" quality and yet it has great, full body, timber and volume. There's a distinctive gentle-of-heart thing going on, too; can hear it in the TONE.