Biosonar echo delay resolution was investigated in four bottlenose dolphins (Tursiops truncatus) using a “jittered” echo paradigm, where dolphins discriminated between electronic echoes with fixed delay and those whose delay alternated (jittered) on successive presentations. The dolphins performed an echo-change detection task and produced a conditioned acoustic response when detecting a change from non-jittering echoes to jittering echoes. Jitter delay values ranged from 0 to 20 μs. A passive listening task was also conducted, where dolphins listened to simulated echoes and produced a conditioned acoustic response when signals changed from non-jittering to jittering. Results of the biosonar task showed a mean jitter delay threshold of 1.3 μs and secondary peaks in error functions suggestive of the click autocorrelation function. When echoes were jittered in polarity and delay, error functions shifted by approximately 5 μs and all dolphins discriminated echoes that jittered only in polarity. Results were qualitatively similar to those from big brown bats (Eptesicus fuscus) and indicate that the dolphin biosonar range estimator is sensitive to echo phase information. Results of the passive listening task suggested that the dolphins could not passively detect changes in timing and polarity of simulated echoes.

中文翻译：

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海豚回声延迟分辨率用抖动回声范式测量。

使用“抖动的”回声范例对四只宽吻海豚（Tursiops truncatus）中的生物声波回声延迟分辨率进行了研究，其中海豚区分了具有固定延迟的电子回声和在连续演示中延迟交替（抖动）的电子回声。当检测到从非抖动回声到抖动回声的变化时，海豚执行回声变化检测任务并产生条件声响应。抖动延迟值的范围为0到 20μs。还进行了被动监听任务，其中海豚听模拟的回声，并且当信号从非抖动变为抖动时产生条件性的声学响应。生物声纳任务的结果显示平均抖动延迟阈值为 1.3μ误差函数中的s和次要峰表示点击自相关函数。当回波在极性和延迟上抖动时，误差函数会偏移大约 5μs，并且所有海豚都可以分辨出仅在极性上抖动的回波。结果在质量上与大棕蝙蝠（Eptesicus fuscus）相似，表明海豚生物声纳距离估计器对回波相位信息敏感。被动收听任务的结果表明，海豚无法被动地检测到模拟回声的时间和极性变化。