Jazz bassist-vocalist Kate Davis is just 19, but her great range and impressive technique have already won critical raves, along with gigs at New York’s legendary Blue Note and the White House. This month she performs at the Ringling International Arts Festival, where audiences may think they’re listening to an old jazz soul. Davis fell in love with the bass just before high school, pushing her way through those first painful blisters to discover a gift for jazz’s improvisatory style. “I didn’t want to follow the rules of classical music,” Davis says. “In jazz, doing something different is encouraged.” Now in her second year at the Manhattan School of Music and a frequent festival performer, she says that when she’s not playing music, “I like to write it.”