National Marine Mammal Foundation, 2240 Shelter Island Drive, Suite 200, San Diego, California 92106, USA.
J Acoust Soc Am. 2011 Feb;129(2):1073-80. doi: 10.1121/1.3523431.
Echolocating dolphins emit trains of clicks and receive echoes from ocean targets. They often emit each successive ranging click about 20 ms after arrival of the target echo. In echolocation, decisions must be made about the target--fish or fowl, predator or food. In the first test of dolphin auditory decision speed, three bottlenose dolphins (Tursiops truncatus) chose whistle or pulse burst responses to different auditory stimuli randomly presented without warning in rapid succession under computer control. The animals were trained to hold pressure catheters in the nasal cavity so that pressure increases required for sound production could be used to split response time (RT) into neural time and movement time. Mean RT in the youngest and fastest dolphin ranged from 175 to 213 ms when responding to tones and from 213 to 275 ms responding to pulse trains. The fastest neural times and movement times were around 60 ms. The results suggest that echolocating dolphins tune to a rhythm so that succeeding pulses in a train are produced about 20 ms over target round-trip travel time. The dolphin nervous system has evolved for rapid processing of acoustic stimuli to accommodate for the more rapid sound speed in water compared to air.
回声定位海豚发出一连串的咔哒声，并从海洋目标接收回声。它们通常在目标回声到达后约 20 毫秒发出下一个测距咔哒声。在回声定位中，必须对目标（鱼类或禽类、捕食者或食物）做出决策。在对海豚听觉决策速度的首次测试中，三只宽吻海豚（Tursiops truncatus）在计算机控制下，随机、无预警地快速连续呈现不同的听觉刺激，选择哨声或脉冲爆发作为响应。这些动物被训练将压力导管保持在鼻腔中，以便可以使用产生声音所需的压力增加来将响应时间 (RT) 分为神经时间和运动时间。当 youngest 和 fastest 海豚对音调做出反应时，平均 RT 范围为 175 至 213 毫秒，对脉冲序列做出反应时，平均 RT 范围为 213 至 275 毫秒。最快的神经时间和运动时间约为 60 毫秒。研究结果表明，回声定位海豚会调整节奏，以便在一连串脉冲中，每个脉冲之间的间隔约为目标往返旅行时间的 20 毫秒。与空气相比，海豚的神经系统已经进化为快速处理声刺激，以适应水中更快的声速。
