KATHY HIRSH-PASIK:"Children need the interactive back-and-forth. We call it 'reciprocity." Campbell says she likes to sing to her baby. COVINGTON CAMPBELL:"He smiles a lot when we sing to him.He definitely reacts to it,it sort of calms him down a little bit." Carol Pearson,VOA News.KATHY HIRSH-PASIK: "Children need the interactive back-and-forth. We call it 'reciprocity.'" Campbell says she likes to sing to her baby. COVINGTON CAMPBELL: "He smiles a lot when we sing to him. He definitely reacts to it, it sort of calms him down a little bit." Carol Pearson, VOA News