Antiphonal is a term used in music to describe a style of singing or playing in which two or more groups alternate with each other. Some synonyms for antiphonally include responsively, alternately, and call-and-response. These terms all indicate a sense of back-and-forth exchange or dialogue, and can be applied not only to music but to any communication between two or more parties. Another related term is choral, which describes a type of singing that involves multiple voices or groups. Whatever word you choose, the important thing is to capture the dynamic and interactive nature of antiphonal music and communication.