TYMPANON, or TYMPANUM  (Gr. rbg ravov, from T117rTEaV, to strike), a name applied by the Romans to both kettledrum and tambourine, in the case of the latter sometimes qualified by leve . The tympanum leve, generally included among the tympana, described as being like a. sieve, was the tambourine used in the rites of Bacchus and Cybele . Pliny doubtless described half pearls having one side round and the other flat, as tympania, on account of their resemblance to the tympanum or kettledrum, which, in its primitive form, innocent of screws or mechanism for tightening the head, exactly resembled the half pearl . During the middle ages the tympanum was gene-rally a tambourine, the kettledrum being known as nacaire . In architecture the term tympanum is given to the triangular space enclosed between the horizontal cornice of the entablature and the sloping cornice of the pediment . Though sometimes left plain, in the most celebrated Greek temples it was filled with sculpture of the highest standard ever attained . In Romanesque and ' Gothic work the term is applied to the space above the lintel or architrave of a door and the discharging arch over it, which was also enriched either with geometrical patterns or in later work with groups of figures; those in continental work are usually arranged in tiers . The upper portion of a gable when enclosed with a horizontal string-course, is also termed a tympanum .