A field cricket’s solutions to the cocktail party problem in conspecific choruses

Many animals signal in choruses to attract mates and reduce predation risk, but simultaneous signaling creates acoustic masking which impairs signal detection and recognition, akin to the cocktail party problem. The severity of interference is likely to be higher in conspecific choruses due to higher signal similarity between signalers, ruling out acoustic niche partitioning as seen in heterospecific choruses. In this study, we examined conspecific masking avoidance in conspecific choruses of a field cricket, Acanthogryllus asiaticus. Field-based measurements revealed that males call from choruses of up to 19 males, with the average nearest neighbor distance between males being 3 m. Transmission experiments showed that the calls of the males transmit up to 3 m and a focal male was likely to have two maskers on average, of which one would fall within the hearing distance of the focal male. In absence of any masking avoidance strategies, the average active space overlap, calculated across ten natural choruses, was found to be 40% and as high as 98%. However, field measurements suggested that focal males actively adjusted call timings to alternate with the audible masker. This was subsequently confirmed in controlled lab playback experiments. Thus, male spacing, limited sound transmission along the ground, and precise adjustment of call timings together reduced average acoustic overlap between maskers to诸多动物会以合唱的方式传递信号，以此吸引配偶并降低被捕食风险。但同时发声会产生声学掩蔽效应，损害信号的检测与识别能力，这类似鸡尾酒会问题（cocktail party problem）。由于同种信号个体间的信号相似度更高，同种合唱中的干扰严重程度往往更高，因此无法像异种合唱那样采用声学生态位划分的策略规避干扰。本研究以亚洲棘蟋（Acanthogryllus asiaticus）的同种鸣唱合唱群体为对象，探究了其同种掩蔽规避行为。野外实地测量显示，雄性个体的合唱群体最多可包含19只雄虫，雄虫间的平均最近邻距离为3米。传声实验结果表明，雄虫的鸣叫声最远可传播3米，单只目标雄虫平均会受到2个掩蔽声源的干扰，其中至少1个处于目标雄虫的听觉感知范围内。若不采取任何掩蔽规避策略，对10个自然合唱群体的计算结果显示，平均有效空间重叠率可达40%，最高甚至达到98%。但野外测量结果表明，目标雄虫会主动调整鸣唱时机，以避开可被其感知到的掩蔽声源。这一现象随后在可控的实验室回放实验中得到了验证。综上，雄虫的空间分布、地面传声的局限性，以及精准的鸣唱时机调整，共同将掩蔽声源间的平均声学重叠率降至