The 39-year-old Australian songtress has been taking advice from the London-born singer to get over the problem, reported Female First.
"I can't sing any of my songs in the key I originally recorded them in. I don't know how those kids on 'The X Factor' do it - it's crazy how they hit the high notes.
"Adele gave me a great tip if I ever tour my songs - before hitting the high notes I'll turn the microphone on the audience and let them do it!," Sia said.
"We were writing it for her new album but it didn't fit with the other tracks so she rejected it. I sent it to Rihanna's people and they rejected it, but in the meantime everyone said I should do it myself.