Equipe Audition, Département d'Etudes Cognitives, Ecole Normale Supérieure, 29 rue d'Ulm, 75230 Paris, France.
J Acoust Soc Am. 2011 Feb;129(2):1100-10. doi: 10.1121/1.3533693.
When foraging, so-called FM-bats emit sequences of frequency modulated (FM) calls in order to detect, identify, and localize edible prey. Once a potential target has been detected, various call and call sequence parameters, such as frequency sweep, pulse duration, and inter pulse interval (IPI) vary. In this paper, the possible functions of the variation of the IPI are studied. In particular, it is conjectured that the IPI patterns are an adaptive behavior that optimizes the signal design parameters in order to improve information retrieval. Such an irregular sampling strategy would be useful whenever bats need to characterize signal modulation (e.g., the wing beat of an insect) using a call emission rate lower than the signal modulation of interest. This problem can be recast as extracting features, in this case the joint acoustic and modulation frequency representation, from signals sampled at frequencies well below the Nyquist cut-off frequency. To study the possibility of such target classification using a sub-Nyquist sampling scheme, results derived in the context of compressive sensing are used. Processing echoes collected from both rotating computer fans and fluttering locusts, it is shown that such a strategy would allow FM-bats to discriminate between targets based on their different fluttering rates.
当觅食时，所谓的 FM 蝙蝠会发出一系列调频（FM）叫声，以检测、识别和定位可食用的猎物。一旦发现潜在的目标，各种叫声和叫声序列参数，如频率扫描、脉冲持续时间和脉冲间隔（IPI）都会发生变化。在本文中，研究了 IPI 变化的可能功能。特别是，有人推测，IPI 模式是一种自适应行为，它优化了信号设计参数，以提高信息检索的效率。当蝙蝠需要使用低于感兴趣信号调制的叫声发射率来描述信号调制（例如昆虫的翅膀拍打）时，这种不规则的采样策略将非常有用。这个问题可以重新表述为从低于奈奎斯特截止频率的频率对信号进行采样，以提取特征，在这种情况下是联合声学和调制频率表示。为了研究使用亚奈奎斯特采样方案进行这种目标分类的可能性，使用了在压缩感知背景下得到的结果。通过处理从旋转计算机风扇和飞舞蝗虫收集的回波，结果表明，这种策略将允许 FM 蝙蝠根据其不同的飞舞速度来区分目标。
