大蹄蝠多普勒正负补偿效应的声波特征与比较
Characterization and comparison of the doppler compensation acoustic wave in Hipposideros armiger
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摘要: 利用单摆装置模拟大蹄蝠的飞行状态并实时记录其回声定位信号, 以研究其多普勒频移补偿行为。与其静息状态下的超声波特征比较, 发现大蹄蝠在接近目标的过程中有多普勒正补偿效应:叫声频率随相对速度改变而成正相关变化; 当相对速度最大时, 其叫声频率相对静息状态频率降低最多, 而相对速度为零时, 叫声频率回复到静息时频率。而当大蹄蝠远离目标时, 有多普勒负补偿效应: 叫声频率随相对速度改变成正相关变化, 叫声频率在相对速度最大时, 升高最多, 但相同速度下升高之值较正补偿值低得多。另外, 负补偿效应出现的频率较正补偿值低, 这可能是由蝙蝠生理结构的限制以及自然状态下罕见的多普勒负补偿条件所决定。Abstract: We used the pendulum device to study Doppler-shifted compensation ofgreat leaf-nosed bat(Hipposideros armiger). The bats’ echolocation calls were recorded by the Ultrasound Detector both under the rest condition and Doppler shift condition. Then we analyzed the calls with Avisoft software. Our results suggested that when H. armiger was approaching the target, it showed positive Doppler shift compensation: call frequency and the velocity (v) were positive correlated. Call frequency fell to minimum when the bats’ relative velocity reached to maximum; likewise call frequency raised to the resting condition frequency when the relative velocity became zero. Negative Doppler shift compensation occurred when bats were far away from the target. Under negative Doppler shift compensation condition, we found call frequency and velocity were positive correlated as well, and moreover, call frequency raised to maximum again while the bats had their minus direction’s maximal relative velocity. However, under this status, the elevated value was much lower than the depressed value under positive compensation at the same velocity. The frequency of occurrence of negative compensation was obviously less frequent than that under positive compensation condition. Therefore, we inferred that the two characteristics of the negative Doppler shift compensation mentioned above may be the coactions consequence of the bio-structural restriction and natural selection.