黑蝉(C.atrata Fabricius.)鸣声的方向性和第三气门的功能

黑蝉鸣声的波形结构无明显的方向性.单音节的重复周期和调幅脉冲列的间隔(I_1和I_2)分别为9.787±0.813ms、2.286±0.093ms和1.874±0.063ms.幅值特性有明显的方向性.主峰频率(MPF=5.47±0.11kHz)的幅值,头向和背向分别比尾向下降5.9dB和3.9dB,侧向和腹向分别增高1.1dB和2.3dB.两侧第三气门受阻后鸣声的波形结构和音色都产生明显变化.I_1和I_2分别为0.912±0.156ms和1.099±0.113ms,约为正常值的40—59%.有三个谱带,MPF为5775Hz,两侧谱带的峰值频率为4575Hz和7025Hz,分别下降1.5dB和3.4dB.

DIRECTIVITY OF SONGS IN BLACK CICADA (C.atrata Fabricius.) AND FUNCTION OF THIRD SPIRACLE

No obvious directivity occurs in the songs of black cicada. Therepetition period of the syllable and the interval (I1 and I2) between the amp-Itiude-modulation pulse trains are 9.787 ± 0.813ms,2.286 ± 0.093ms and 1.874 ± 0.063ms, respectively. The amplitude property is possessed of the marked directivity. The amplitude of the main peak frequency (MPF=5.74±0.11kHz) in the song toward head and dorsum is 5.9dB and 3.9dB lower than that of the song toward tail respectively, and in the song toward latero-side and venter increase by 1.1dB and 2.3dB respectively.The significant change of the acoustic waveform structure and the timbre occur in the song after blocking of the third spiracle on both sides. The I1 and I2 are 0.912 ±0.156ms and 1.099 ± 0.113ms respectively, and about 40-59% of that in normal solo. There are three spectral bands, the MPF is 5775Hz, and the peak frequency of spectral band on both sides of the MPF is 4575Hz and 7025Hz and is 1.5dB and 3.4dB lower than that of the MPF respectively.