Washington native Shirley Horn, interpreting the music of Duke Ellington at the Corcoran yesterday, proved that she is an unmined local treasure. In a voice that was soft, even dry, she lent deep personal meaning to song after song with a verbal precision and vibratoless timbre that would, in a less intimate singer, negate emotive power.

Horn's magic of communication was there on a wistful "I Let a Song Go Out of My Heart" and on a light-as-air and bell-toned "Solitude." She commenced "Come Sunday" in bedside prayer intonation and finished it with a shouted-from-the-pulpit plea.

"It Don't Mean a Thing If It Ain't Got That Swing" displayed the boisterous side of Horn as she, her scatting voice topping in sync with drummer Stump Saunders' cracking rim shots, pours into the piece as though egged on by a Savoy Ballroom crowd. Horn's self-accompaniment at the piano put voice and instrument in unerring relationship and her several voiceless features were ruminative and uncluttered. Charles Ables was appropriately subdued on electric bass.

The Great American Songwriters series continues with Dave Frishberg on Hoagy Carmichael and his own compositions on Nov. 1.