Cvikel Noam, Levin Eran, Hurme Edward, Borissov Ivailo, Boonman Arjan, Amichai Eran, Yovel Yossi
Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
Department of Entomology, University of Arizona, Tuscon, AZ 85721, USA.
Proc Biol Sci. 2015 Jan 7;282(1798):20142274. doi: 10.1098/rspb.2014.2274.
Animals often deal with situations in which vast sensory input is received simultaneously. They therefore must possess sophisticated mechanisms to select important input and ignore the rest. In bat echolocation, this problem is at its extreme. Echolocating bats emit sound signals and analyse the returning echoes to sense their environment. Bats from the same species use signals with similar frequencies. Nearby bats therefore face the difficulty of distinguishing their own echoes from the signals of other bats, a problem often referred to as jamming. Because bats commonly fly in large groups, jamming might simultaneously occur from numerous directions and at many frequencies. Jamming is a special case of the general phenomenon of sensory segregation. Another well-known example is the human problem of following conversation within a crowd. In both situations, a flood of auditory incoming signals must be parsed into important versus irrelevant information. Here, we present a novel method, fitting wild bats with a miniature microphone, which allows studying jamming from the bat's 'point of view'. Previous studies suggested that bats deal with jamming by shifting their echolocation frequency. On-board recordings suggest otherwise. Bats shifted their frequencies, but they did so because they were responding to the conspecifics as though they were nearby objects rather than avoiding being jammed by them. We show how bats could use alternative measures to deal with jamming instead of shifting their frequency. Despite its intuitive appeal, a spectral jamming avoidance response might not be the prime mechanism to avoid sensory interference from conspecifics.
动物常常要应对同时接收到大量感官输入信息的情况。因此，它们必须具备复杂的机制来筛选重要信息并忽略其余信息。在蝙蝠的回声定位中，这个问题尤为突出。回声定位的蝙蝠会发出声音信号，并分析返回的回声以感知周围环境。同一物种的蝙蝠使用频率相似的信号。因此，附近的蝙蝠面临着将自己的回声与其他蝙蝠的信号区分开来的困难，这个问题通常被称为干扰。由于蝙蝠通常成群飞行，干扰可能同时从多个方向、以多种频率出现。干扰是感官分离这一普遍现象的一个特殊情况。另一个广为人知的例子是人类在人群中跟上对话的问题。在这两种情况下，大量传入的听觉信号都必须被解析为重要信息和无关信息。在这里，我们提出了一种新颖的方法，给野生蝙蝠安装一个微型麦克风，这使得我们能够从蝙蝠的“视角”研究干扰。先前的研究表明，蝙蝠通过改变回声定位频率来应对干扰。机上录音显示情况并非如此。蝙蝠确实改变了它们的频率，但这样做是因为它们把同种蝙蝠当作附近的物体做出反应，而不是为了避免被它们干扰。我们展示了蝙蝠如何能够使用其他措施来应对干扰，而不是改变频率。尽管频谱干扰避免反应直观上很有吸引力，但它可能不是避免同种蝙蝠产生感官干扰的主要机制。
