Tympanum. Usually, either a semi-circular board filling the top part of an archway, or a semi-circular design in stone, typically above a Norman doorway. A tympanum board in the chancel arch carried a doom painting before the Reformation, and the royal arms afterwards. The rood was sometimes fixed to it. Some were revealed in the 19th century, most famously that at Ludham. Some are modern, and put up for no other reason than to suspend curtains from, partitioning the chancel from the nave, for smaller congregations.