The Tucson Symphony Orchestra Chorus holds auditions by appointment on Saturday, May 18. Call 620-9152 for an appointment. Applicants should be able to sight read, have a pleasant singing voice, and be able to adapt to various repertoire. They should prepare to sing a solo chosen from the opera or art-song literature. Rehearsals are from 7 to 9:30 p.m., every Monday at the Symphony Center.