TIMBRE VARIATIONS OF THE CALLING SONGS OF THE CICADA CRYPTOTYMPANA ATRATA FABRICIUS
蚱蝉(Cryptotympana atrata Fabricius)自鸣声音色的变化

The timbres of the calling songs of the cicada C. atrata in Beijing can be classified into monotones, dual tones and triple tones1]. In this paper, the variation of each timbre and the energy of the main timbre affected by higher amplitude pulse have been clarified further.The timbre variation of the calling songs of the cicada C. atrata imports mainly the pronounced variations of the main timbre frequency spectra (MTF) . MTF of the calling song of the monotone changes mainly within frequency band 4.1 - 5.8kHz: that of the dual timbre mianly within 3.6-5.4kHz and has reverse phenomenon with the frequency of the secondary timbre in each other ; and that of the triple timbre is although in narrower frequency band 3.5-4.5kHz. the three tonal peaks are very approximate in energy and show clearly three kinds of tonal components.The calling songs of cicada C. atrata have approximately biggest amplitudes in distinct sections of the songs, but the amount of the higher pulses are different, which corresponds to the energy of the main timbre in these song sections.