Schmidt S
Zoologisches Institut Universität, München, FRG.
Nature. 1988 Feb 18;331(6157):617-9. doi: 10.1038/331617a0.
Bats obtain information about the structure of objects in the outside world from their echolocation signals, an extremely useful method when hunting non-flying prey in densely cluttered habitats, for example. Information about object structure is contained both in the time and in the spectral interference patterns of signals reflected from surfaces at different distances from the bat. I report here an experiment designed to test the extent to which bats use these two types of information. A 'phantom target' is generated by playing back to an echolocating bat signals that mimic the result of reflection from two planes set at different distances. The ability of the bat to discriminate between two such targets is investigated as a function of the separations of the planes. Several of the results do not fit the hypothesis that the bat simply uses time-delay information: the very small time difference that can be discriminated, the fall off in ability to discriminate planes at a particular separation and the symmetry of the discrimination ability measured in the frequency domain. The empirical data can best be fitted by a function based on spectral correlation.
蝙蝠通过回声定位信号获取外界物体结构的信息，例如，在密集杂乱的栖息地捕食非飞行猎物时，这是一种极其有用的方法。关于物体结构的信息既包含在时间中，也包含在从距蝙蝠不同距离的表面反射的信号的频谱干涉模式中。我在此报告一项实验，旨在测试蝙蝠利用这两种信息的程度。通过向一只正在进行回声定位的蝙蝠回放模拟从设置在不同距离的两个平面反射结果的信号，生成一个“虚拟目标”。研究蝙蝠区分两个这样的目标的能力与平面间距的函数关系。一些结果不符合蝙蝠仅使用时间延迟信息的假设：可区分的非常小的时间差、在特定间距下区分平面的能力下降以及在频域中测量的区分能力的对称性。经验数据最好由基于频谱相关性的函数拟合。
