The Sing-Off Season Four Premiere Recap: All In -- Vulture: Element are the Barden Belles of The Sing-Off, except they’re all Anna Camp. Their version of Ellie Goulding’s “Burn” is super sterile and immediately forgettable. But Jewel tells us that women only have two octaves in their chest voice, so female singers are forced to do more with less. This is information that is actually good to know.