Singing from rooftops

Their musical performances pack university auditoriums, though they play no instruments.

While universities have long nurtured the niche community of a cappella singers, the TV show Glee and hit movie Pitch Perfect helped create a new generation of fans that propelled the soulful, unaccompanied vocal sound into mainstream culture. Now, they're unlikely stars on campuses across the United States.

On Saturday, about 3,000 people will flock to New York to see eight groups compete in the collegiate championship of a cappella singings. The sold-out show at the Beacon Theatre is a far cry from the paltry crowd of 200 that watched the national finals more than a decade ago.