Hingham’s Unicorn Singers will host an open sing and auditions for the public on July 30 at 7:30 p.m. The group is a volunteer organization that performs throughout the South Shore. According to founder and director Margo Euler, the event is intended to introduce potentially interested singers to the repertoire of chamber music the group performs as well as attract high-quality singers. Music will be provided for those wishing to join in the concert. Auditions for those interested in joining the group will take place at the end of the evening. “It will be a chance to show you’re interested,’’ Euler said. “”It depends how many come and how many want to explore singing with us. But it’s by reservation only, and I plan to personally acquaint them with what we do.’’ For more information, e-mail email@example.com .