Music: Imported Export

The difference between bop and Dixieland musicians, Jazzman Eddie Condon once cracked, is that bop men flat their fifths, whereas Dixielanders drink theirs.

Pia Beck, 30, a Dutch pianist who is sometimes called "the Flying Dutchess.'' cannot tell a fifth from a fipple flute, but that does not keep her from bopping along on the cool side of the street and leaving the sunny side to Dixielanders. When Pia took off after a vocal chorus in English last week at the Tijuana, a Baltimore nightclub, listeners cried. "Hey, this chick's not from Europe—she's from Brooklyn!"

Big, blonde and bustling, Pia is one in...