Guilment Thomas, Sidorovskaia Natalia, Li Kun
Physics Department, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, USA.
J Acoust Soc Am. 2020 May;147(5):3605. doi: 10.1121/10.0001266.
This paper investigates the evolution of spectral properties observed in Cuvier's beaked whale (Ziphius cavirostris) click trains recorded by fixed hydrophones in the Gulf of Mexico. In the context of deep water and high-frequency sounds and observed inter-click intervals, the authors assumed that the main effect responsible for the modification of the spectral content between adjacent clicks in the same click train is the source beam pattern. The spectral structure is studied by using the Wigner-Ville time-frequency distribution and is compared with the conventional Fourier spectrogram. The results show that the observed Cuvier's beaked whale clicks are a superposition of upsweep and downsweep chirps, unlike the currently accepted upsweep only structure of beaked whale clicks in bioacoustics literature. The spectral structure variations simulated by using a flat circular piston model as a beam pattern transmission model are consistent with the evolution of spectral click properties observed in experimental data. A better understanding of the properties of observed echolocation clicks of Cuvier's beaked whales will provide useful information for click annotations and, therefore, will contribute to improving accuracy of detecting, classifying, tracking, and estimating the density of Cuvier's beaked whales.
本文研究了在墨西哥湾由固定水听器记录的柯氏喙鲸（Ziphius cavirostris）滴答声序列中观察到的频谱特性演变。在深水和高频声音以及观察到的滴答间隔的背景下，作者假设，在同一滴答声序列中，导致相邻滴答声频谱内容改变的主要因素是声源波束模式。通过使用维格纳-威利时频分布研究频谱结构，并将其与传统傅里叶频谱图进行比较。结果表明，观察到的柯氏喙鲸滴答声是上升扫频和下降扫频啁啾声的叠加，这与生物声学文献中目前公认的喙鲸滴答声仅为上升扫频结构不同。使用扁平圆形活塞模型作为波束模式传输模型模拟的频谱结构变化与实验数据中观察到的滴答声频谱特性演变一致。更好地了解观察到的柯氏喙鲸回声定位滴答声的特性，将为滴答声注释提供有用信息，因此，将有助于提高柯氏喙鲸检测、分类、跟踪和密度估计的准确性。
