DYNAMIC PROPERTIES OF ASSISTANT SOUNDER IN BLACK CICADA (C.atrata FABRICIUS)

The dynamic properties of the assistant sounders in the black cicada are given and the twitching properties of Contraction in the sounding muscle are revealed in this paper.For the operculum, tymbal cover and joint membrane, each of their vibration periods consists of three subgroup vibrations (SGVa,b,c) corresponding to amplitude-modulation pulse trains (AMPT1,2,3) in every syllable of synchro song. In comparison with the vibration at dorsum, the SGVa-c have a subband with the function of regulating the tone. During calling song continuously, the pressure change inside the resonant cavity and the airspeed through the spiracles on both sides are about 7. 94—15.88 Paand 0.59—0.84 cm3/s respectively, and they increase by about 7 and 2.6 times as the abdomen is moved. When the contraction motion of the sounding muscle comes up to the critical Sounding state, it further produces the twitching process, and drives the sounding membrane and the toning plate-membrane to produce AMPT1-3 and SGV(a