Membership in a lighthearted vocal group is a fond memory for many college graduates. For others, including more than a few celebrities, a year or two in a cappella is something they'd rather forget. Mickey Rapkin, author of the book “Pitch Perfect: The Quest for Collegiate A Cappella Glory” and a senior editor at GQ magazine, explains why a cappella is a polarizing force -- one that might be going mainstream.

Our blog: John Schaefer on a cappella groups.

Tell us: Are you an alumnus or alumna of an a cappella group? How do you look back at your time in one?