Tymbal (or timbal) is a term for a corrugated exoskeletal structure used to produce sounds in insects. In male cicadas, the tymbals are membranes in the abdomen, responsible for the characteristic sound produced by the insect.

tymbal mechanism and song patterns of the bladder cicada, Cystosoma saundersii
Tymbal mechanics and the control of song frequency in the cicada Cyclochila australasiae
Neuromuscular Junctions in Flight and Tymbal Muscles of the Cicada
The Tymbal: Evolution of a Complex Vibration-Producing Organ in the Tymbalia (Hemiptera excl. Sternorrhyncha)
Asymmetry of tymbal action and structure in a cicada: A possible role in the production of complex songs
Functional organization of the arctiid moth tymbal (Insecta, Lepidoptera).
Morphology of the Tymbal Organ of the Potato Leafhopper Empoasca fabae Harris (Homoptera: Cicadellidae)
The Closed-Loop Nature of the Tymbal Response in the Dogbane Tiger Moth, Cycnia tenera (Lepidoptera, Arctiidae)
Mechanical properties of glycerinated fibres from the tymbal muscles of a Brazilian cicada
Sound production by abdominal tymbal organs in two moth species: the green silver-line and the scarce silver-line (Noctuoidea: Nolid...