<P> Only the studio recording of the contestants' performances, not the live performance, are available on iTunes . In the first season, the battle rounds were recorded in the studio with both artists in the pairing . However, from season two on, only the winner's version of the song from the battle round is released . Season seven reverted to the old style of both artists . With the introduction of the Knockout Rounds in season three, where each contestant sang a separate song, only the winner's single is released . </P> <P> The "Instant Save" was introduced in season five . During the live elimination episodes, viewers are given a five - minute window to vote for the contestants in danger of elimination by using their Twitter account to decide which contestant will move on to the next show, starting with the Top 12 . Home viewers can only vote once per account for one contestant of their choice . </P> <P> CeeLo Green of Gnarls Barkley and Adam Levine of Maroon 5 became the first confirmed coaches in February 2011, followed by Christina Aguilera and Blake Shelton in March . Aguilera and Green did not return for season four and were replaced by Shakira and Usher as substitute coaches . Aguilera and Green then returned for season five, while Shakira and Usher returned for season six . In an interview with Ellen DeGeneres in February 2014, Green revealed that he would not be returning to The Voice . On March 31, 2014, it was announced that Pharrell Williams would become Green's replacement . On April 19, 2014, it was announced that No Doubt's Gwen Stefani would replace Aguilera in season seven due to her pregnancy . On May 20, 2014, Shakira and Usher confirmed that after season six, they would focus on their music . On March 25, 2016, Miley Cyrus confirmed that following her role as key advisor during the tenth season that she would be joining the series once again in its eleventh season as a coach, replacing Christina Aguilera . That same day, Alicia Keys was also announced to be joining the series as a coach for the eleventh season . On October 18, 2016, it was announced that Stefani would re-join the coaches' panel for the series' twelfth season, alongside returning coaches Keys, Levine and Shelton; it was also confirmed that Cyrus would return for the thirteenth season . </P> <P> On April 27, 2017, in an interview published by TV Insider, Keys confirmed that the twelfth season would be her last . She stated, "Who knows what the future holds, but I know this one is my final season ." On May 10, 2017, NBC announced that Jennifer Hudson would join the coaches lineup for the series' thirteenth season . On May 11, 2017, it was announced that Kelly Clarkson would be a coach in season fourteen in 2018 . </P>

Who were the judges last year on the voice
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