University of California San Diego, Serf Building, Room 295 0435, 9500 Gilman Drive, La Jolla, California 92093, USA.
J Acoust Soc Am. 2012 Aug;132(2):1213-21. doi: 10.1121/1.4730900.
A two-dimensional array of 16 hydrophones was created to map the spatial distribution of different frequencies within the echolocation beam of a Tursiops truncatus and a Pseudorca crassidens. It was previously shown that both the Tursiops and Pseudorca only paid attention to frequencies between 29 and 42 kHz while echolocating. Both individuals tightly focused the 30 kHz frequency and the spatial location of the focus was consistently pointed toward the target. At 50 kHz the beam was less focused and less precisely pointed at the target. At 100 kHz the focus was often completely lost and was not pointed at the target. This indicates that these individuals actively focused the beam toward the target only in the frequency range they paid attention to. Frequencies outside this range were left unfocused and undirected. This focusing was probably achieved through sensorimotor control of the melon morphology and nasal air sacs. This indicates that both morphologically different species can control the spatial distribution of different frequency ranges within the echolocation beam to create consistent ensonation of desired targets.
创建了一个由 16 个水听器组成的二维数组，以绘制 Tursiops truncatus 和 Pseudorca crassidens 回声定位波束内不同频率的空间分布。先前的研究表明，Tursiops 和 Pseudorca 在回声定位时仅关注 29 至 42 kHz 之间的频率。这两个个体都将 30 kHz 的频率紧密聚焦，并且焦点的空间位置始终指向目标。在 50 kHz 时，波束的聚焦程度较低，并且不太精确地指向目标。在 100 kHz 时，焦点经常完全丢失，并且不指向目标。这表明这些个体仅在其关注的频率范围内主动将波束聚焦到目标上。该范围之外的频率则没有被聚焦和定向。这种聚焦可能是通过对瓜形态和鼻囊的感觉运动控制来实现的。这表明，两种形态不同的物种都可以控制回声定位波束中不同频率范围的空间分布，从而产生对期望目标的一致声纳效应。
