Unlike opera or the art song, popular music has never had any pretensions of profundity or grandiosity. The popular song speaks of simple matters, simply, and its power depends on the voice of its interpreter to give if life and character.

Barbara Cook is just such a singer. Appearing last night through Sunday, and extended (from Dec. 21 to 23) at the Waaay Off Broadway, she displayed an affection for her material that gave it a breath of feeling that sent shivers down the spine and brought an occasional chuckle and tear.

She doesn't sing the songs, she embraces them, caressing the lyrics softly and snuggling up to the melodies. Her warm, rich voice was like smooth velvet on the quiet ballads and reached for loud brassy high notes on the faster-paced numbers. She also has a wry with that lightens her show and she seems to revel in teasing and joking with her listeners.

For her final number, Cook sang "Nothing Could Be Finer Than to Be in Carolina." The song began slowly, with a bluesy bass line that continued to build as she reached for a low-note or two and then sent the words flying off to the chandeliers with a rousing finale that had the capacity crowd on its feet and cheering.