National Marine Mammal Foundation, 2240 Shelter Island Drive, #204, San Diego, California 92106, USA.
J Acoust Soc Am. 2013 Sep;134(3):2274-85. doi: 10.1121/1.4816404.
Dolphins are hypothesized to deduce the swimming direction of group members by attending to the spectral pattern of whistle harmonics. This is known as the direction of movement cue hypothesis and may facilitate coordination of complex group behavior when visibility is poor. The direction of movement cue hypothesis hinges on the assumption that dolphins can discriminate between whistles with different harmonic patterns that are associated with signaler orientation. This assumption was tested with a bottlenose dolphin. Whistles were recorded from a dolphin at different azimuth positions (0° to 180° in 45° increments). Noise-free, synthetic whistles were created to mimic the direction-dependant spectral profiles of the recorded whistles. A dolphin was then tested in its ability to discriminate between the synthetic whistles using fixed level and roving level conditions. The dolphin's discrimination performance in both the fixed and roving level conditions was near 100% for whistles separated by angles greater than 45°, and near chance for 45° separations. Computer simulations of the task, along with the dolphin's performance, suggest that the dolphin's discrimination was level invariant and based on the spectral pattern of the whistles.
海豚被假设通过关注哨音谐波的光谱模式来推断群体成员的游动方向。这被称为运动方向线索假说，当能见度较差时，可能有助于协调复杂的群体行为。运动方向线索假说取决于海豚可以区分与信号器方向相关的具有不同谐波模式的哨音的假设。这一假设在一只宽吻海豚身上进行了测试。哨音是从一只海豚在不同的方位角位置（0°到 180°，每隔 45°递增）记录的。无噪声的合成哨音被创建来模拟记录哨音的方向相关光谱特征。然后，海豚在使用固定水平和游动水平条件下被测试其区分合成哨音的能力。海豚在固定和游动水平条件下的辨别性能对于大于 45°的角度分离的哨音接近 100%，而对于 45°的分离接近机会。该任务的计算机模拟以及海豚的表现表明，海豚的辨别是水平不变的，并且基于哨音的光谱模式。
