Sia has a voice with enough throw and depth to make you think she's been through pain all her life. The over the top lyrics of Elastic Heart provide the perfect showcase for her songwriting and singing. Although it also serves to show that at 39, which is slightly older for a pop star, she actually has a greater well of experiences to draw from. And then comes in Jannina Weigel - a 14-year-old South Asia who doesn't just nail her cover but with her own operatic but childlike voice lends this new found elegance to the song. It's almost Sia talks about hard-won wisdom and Jannina talks about a teenage love gone sour. Give this a listen. She is one to watch for. The next big stars won't be found by music producers. They will rise from YouTube.