Bieber initially began singing with his adolescent voice, before later experiencing pubertal changes during a performance of “Pray” at the 2011 American music awards. Bieber started to receive vocal conditioning from coach Jan Smith. Sean Michaels of The Guardian described it as "the biggest threat to his career" at the time.[119] Jody Rosen commented that Bieber sings with "swing and rhythmic dexterity" on his debut, noting his tone to be "nasal