Question: What season of The Voice did the lead vocalist of No Doubt appear on?

full_context: Document 1: The Sweet Escape (song): "The Sweet Escape" is a song by American singer and songwriter Gwen Stefani from her second studio album of the same name (2006). It was written by Stefani, Akon, and Giorgio Tuinfort. Akon, who is also a featured artist, developed the song's beat before collaborating with Stefani. He designed it based on her previous work with No Doubt, and Stefani later commented that it put her "on the yellow brick road to the No Doubt record I might do". "The Sweet Escape" is an apology for a fight between two lovers and describes a dream of a pleasant life for them. As the album's title track, its title was chosen to help market Stefani's music and fashion lines.
Document 2: Jeffery (mixtape): Jeffery (originally titled No, My Name is Jeffery) is a mixtape by American rapper Young Thug. It was released for retail purchase on August 26, 2016, by 300 Entertainment and Atlantic Records. The mixtape features guest appearances from Gucci Mane, Young Scooter, Travis Scott, Wyclef Jean, and Quavo, as well as executive production from TM88 and Wheezy.
Document 3: Jeffery Austin: Jeffery Austin McClelland, Jr. (born April 15, 1991), better known by his stage name Jeffery Austin, is an American pop musician and was a contestant on the ninth season of The Voice, turning a single chair and defaulting to be a member of Gwen Stefani's team. He eventually finished in fourth place, behind Jordan Smith, Emily Ann Roberts, and Barrett Baber. His compilation album, "The Voice: The Complete Season 9 Collection", placed on the "Billboard" magazine charts.
Document 4: Barrett Baber: Barrett Hankins Baber (born May 18, 1980) is an American country musician, where he plays alternative country and country rock music, and who was a contestant on NBC's "The Voice", where he auditioned and got a four chair turn during season nine, and he chose to be a member of team Blake Shelton. His songs have charted on the "Billboard" magazine charts, during his performances on the show. He finished the competition in third place behind winner Jordan Smith and runner-up Emily Ann Roberts.
Document 5: Wind It Up (Gwen Stefani song): "Wind It Up" is a song by American singer and songwriter Gwen Stefani. Originally written for inclusion on Stefani's Harajuku Lovers Tour, the song was later recorded for her second solo studio album, "The Sweet Escape" (2006). The track contains an interpolation of "The Sound of Music" song "The Lonely Goatherd".
Document 6: L.A.M.B.: L.A.M.B. was a fashion line by American singer Gwen Stefani, the lead vocalist of the rock band No Doubt. The line manufactured apparel and fashion accessories. It was founded in 2003 and made its runway debut in 2004. The fashion line manufactured accessories like shoes, watches, bags and a fragrance called "L." The name is an acronym of her debut solo album "Love. Angel. Music. Baby".
Document 7: Harajuku Lovers Tour: The Harajuku Lovers Tour was the first solo concert tour of American recording artist Gwen Stefani. The tour began through October to November 2005, to support of her debut studio album "Love. Angel. Music. Baby." (2004). Although Stefani embarked on multiple tours with her band No Doubt, she initially opted not to participate in a tour to promote her album, an attitude that the singer eventually abandoned due to the commercial success of "Love. Angel. Music. Baby."
Document 8: Jeffree Star: Jeffree Star (born Jeffrey Lynn Steininger on November 15, 1985) is an American singer-songwriter, make-up artist, fashion designer and model from Orange County, California. He started his music career on MySpace with over 25 million plays on his self-released music. After releasing two extended plays, Star released his debut album, "Beauty Killer" (2009), under Popsicle Records. Star is also known for his fashion line, Beauty Forever, and his transgressive, gender-bending appearance and persona.
Document 9: List of songs recorded by Gwen Stefani: American singer and songwriter Gwen Stefani has recorded material for three studio albums and one extended play (EP), and has been featured on songs on other artists' respective albums. After releasing five studio albums with ska punk group No Doubt, in 2004 Stefani began work as a solo artist, developing her pop debut "Love. Angel. Music. Baby." in the same year. It produced several top ten singles worldwide, including "What You Waiting For?", "Rich Girl", and "Hollaback Girl", the latter of which was the first single to sell over a million digital copies in the United States. The record contained work from a variety of producers and songwriters, including Linda Perry, Nellee Hooper, André 3000, and No Doubt bandmate Tony Kanal. "Cool", "Luxurious", and "Crash" were also released as the singles. In 2005, Stefani released an extended play "Love. Angel. Music. Baby. (The Remixes)" and included the Richard X remix of "Cool", which topped the United States Dance Club Songs in November 2005. Hip hop musician André 3000 made two appearances on the album, including on "Long Way to Go", and his alter ego "Johnny Vulture" on "Bubble Pop Electric".
Document 10: This Is What the Truth Feels Like: This Is What the Truth Feels Like is the third studio album recorded by American singer and songwriter Gwen Stefani. It was released on March 18, 2016 by Interscope Records. Initially, the album was scheduled to be released in December 2014 with Stefani working with a handful of high-profile producers, and Benny Blanco serving as executive producer. However, after the underperformance of her 2014 singles and the writer's block Stefani suffered, she did not feel comfortable curating an album and scrapped the whole record in favor of starting again. The album's release was scheduled after Stefani hinted at it on her Twitter account.
Document 11: Jeffree Star discography: The discography of American singer-songwriter Jeffree Star consists of one studio album, three extended plays, five singles and four music videos. After self-releasing an extended play "Plastic Surgery Slumber Party" in 2007, Star founded his own label Popsicle Records. He released his second extended play, "Cupcakes Taste Like Violence", in December 2008. The extended play produced one commercial single, "Lollipop Luxury". In September 2009, Star released his debut studio album, "Beauty Killer". The album produced one commercial single, "Prisoner" and two music videos for "Get Away with Murder" and "Beauty Killer". On October 2, 2012, Star released a four-track single called "Mr. Diva" to tide fans over and play new music on tour. "Mr. Diva" was also released as a limited edition vinyl record with "Legs Up" being the B-side track; it was a red heart shape with 500 copies printed. Star released his single "Love to My Cobain" on June 25, 2013 with the music video being released August 15.
Document 12: Gwen Stefani: Gwen Renée Stefani ( ; born October 3, 1969) is an American singer, songwriter, fashion designer, actress, and television personality. She is a co-founder and the lead vocalist of the band No Doubt that experienced major success after their breakthrough studio album "Tragic Kingdom" (1995) along with various successful singles, including "Just a Girl", "Don't Speak", "Hey Baby", and "It's My Life". During the band's hiatus, Stefani embarked on a solo pop career in 2004 by releasing her debut studio album "Love. Angel. Music. Baby." Inspired by pop music from the 1980s, the album was met with both critical and commercial success. It spawned three commercially successful singles: "What You Waiting For?", "Rich Girl", and "Hollaback Girl", the latter reached number one on the "Billboard" Hot 100 while also becoming the first US download to sell one million copies. In 2006 Stefani released her second studio album "The Sweet Escape". The album produced two successful singles: "Wind It Up" and the album's title track "The Sweet Escape". Her third solo album "This Is What the Truth Feels Like" was released in March 2016 and became her first solo number-one album on the "Billboard" 200.
Document 13: Jeffrey Steele: Jeffrey LeVasseur (born August 27, 1961) is an American country music singer and songwriter, more commonly known by the name Jeffrey Steele. Along with recording his own material, Steele has become a prolific Nashville songwriter, having co-written more than sixty hit songs for such artists as Montgomery Gentry, Tim McGraw, Faith Hill, LeAnn Rimes, Rascal Flatts, Billy Ray Cyrus, and others.
Document 14: What You Waiting For?: "What You Waiting For?" is a song by American singer Gwen Stefani from her debut solo studio album, "Love. Angel. Music. Baby." (2004). Written by Stefani and Linda Perry, the song is the album's opening track and was released as Stefani's debut solo single. "What You Waiting For?" details Stefani's lack of inspiration, fear of producing the album, as well as her reaction to pressures exerted by her record label. It is primarily an electropop song and introduces Stefani's four back-up dancers, the Harajuku Girls, who had a major input into the album's production.
Document 15: Johntá Austin: Johntá Austin ( ; born June 28, 1980) is an American singer-songwriter, arranger and rapper, who is signed to Jermaine Dupri's So So Def Recordings. He is commonly known for collaborating with producers Bryan-Michael Cox, Jermaine Dupri & The Production Team StarGate. Austin was awarded two Grammy Awards for his work on the songs "We Belong Together" by Mariah Carey and "Be Without You" by Mary J. Blige.
ground_truth: ninth