San Francisco Choral Artists will perform new American choral music in a program May 18 presented by Composers, Inc. Magen Solomon directs the 24-voice semi-profession choir, now celebrating their 25th anniversary, in a program that includes Frank La Roccas 2005 Meistersings Choral Competition winning Miserere, an a cappella setting of Psalm 51 in Latin. Pianist Lino Rivera returns this season to join the choir for Trevor Gomes Sunscape for mixed chorus and piano, which depicts the sun from rise to set by means of nonsense sounds mixed with bits of Spanish and French, rich harmonies, driving rhythms, and a jazz sensibility. Beginning in 2005, SFCA has fostered new works from young composers through its New Voices Competition, this year featuring winners Eleanor Ayersa and Kala Pierson.