premise: Backing vocalists cannot ever sing.
hypothesis: Backing vocalist . In some cases , a backing singer may sing alone as a lead-in to the main vocalist 's entry or to sing a counter-melody . In Latin or Afro-Cuban groups , backup singers may play percussion instruments or shakers while singing . In some pop and hip-hop groups and in musical theater , the backup singers may be required to perform elaborately choreographed dance routines while they sing through headset microphones . The style of singing used by backup singers varies according to the type of song and the genre of music the band plays . In hardcore punk or rockabilly , other band members who play instruments may sing or shout backup vocals during the chorus ( refrain ) section of the songs .