Justin Bieber cultivated his chart-clobbering sound with an ear trained on his heroes, from the genre-defying charisma of Michael Jackson and Justin Timberlake to the silky-smooth balladry of Ne-Yo and his own mentor, Usher. These formative gems mix sensitive R&B honesty with modern pop production, plus a vocal suppleness that continues to guide Bieber through new chapters of his career.