Sinfonietta unfurls evocative musical tapestry of a Langston Hughes African-American epic

Preview: Chicago Sinfonietta’s annual Martin Luther King Jr. tribute concert is consistently the orchestra’s best-attended event of the year, says music director Mei-Ann Chen. But this year’s MLK affair – Jan. 15 at Orchestra Hall — will also be Sinfonietta’s most ambitious enterprise: composer Laura Karpman’s musically multicultural setting of Langston Hughes’ epic poem about the African-American experience, “Ask Your Mama.”