Reviewers noted the use of Auto-Tune in Spears' voice. Ewing said that "Blackout" serves as a reminder of how instantly recognizable Spears' vocals are, saying that "treated or untreated: her thin Southern huskiness is one of the defining sounds of 00s pop." He noted that the album "is a masterclass in autotune and vocal treatment as a studio instrument, disrupting and jamming the songs as much as it helps them." While reviewing Spears' demo of "Telephone", Rob Sheffield of "Rolling Stone" compared it to "Piece of Me", "proving yet again how much impact Britney has had on the sonics of current pop. People love to make fun of Britney, and why not, but if 'Telephone' proves anything, it's that "Blackout" may be the most influential pop album of the past five years." In June 2012, "Blackout" was added to the Rock and Roll Hall of Fame's musical library and archive.