As the name of the piece indicates, Vox Balaenae was inspired by whale songs. "Late in the 1960s, George Crumb heard a tape recording prepared by a marine scientist of the sounds emitted by the humpback whale.... In 1971, Crumb drew on these sounds as the inspiration...". Although the piece has eight movements, these are grouped into three structurally similar parts: the first two movements "(...for the beginning of time)", five variations named after geologic time periods, and the last movement "(...for the end of time)"