Short answers, pulled from the story.
The tympanum was a circular, shallow frame drum used in ancient Greece and Rome, similar to a tambourine. It was beaten with the palm of the hand or a stick, and some depictions show decorative or zill-like objects around its rim.
The tympanum was played by worshippers in the rites of Dionysus, Cybele, and Sabazius. It was especially prominent in the cult of Cybele, where it was the most common musical instrument shown in Greek and Roman art and literature associated with her worship.
The earliest depiction of the tympanum in Greek art dates to the 8th century BC. It appears on a bronze votive disc found in a cave on Crete that served as a cult site for Zeus.
From the 6th century BC, images of Cybele as Meter or Magna Mater often show her with the tympanum balanced on her left arm. The Homeric Hymn to the Great Mother states that the goddess loves the sound of the tympanum, and the drum remained a standard attribute of Cybele into the Roman Imperial era.
In depictions of the thiasos, the retinue of Dionysus, the tympanum was typically played by maenads. Satyrs played wind instruments such as pipes or the aulos, while maenads took charge of the drum.
The tympanum came to Rome from Greece and the Near East, likely in connection with the cult of Cybele. Despite Cybele's Anatolian origins, the tympanum does not appear in representations from Anatolia itself, suggesting it became associated with her worship during the cult's westward spread.