Goold J C, Jones S E
University College of North Wales, School of Ocean Sciences, Bangor, Gwynedd, United Kingdom.
J Acoust Soc Am. 1995 Sep;98(3):1279-91. doi: 10.1121/1.413465.
Regular clicks from diving sperm whales, both large bull males and smaller females, were recorded in deep oceanic water off the Azores and subsequently sampled to computer disks for digital analysis. A total of 8540 clicks were marked and analyzed. Simple temporal analysis of the interclick intervals during feeding dives revealed mean click rates for male sperm whales of 1.1713 s-1 and 1.9455 s-1 for females. Fourier analysis showed distinctive peaks in the spectra of bull male sperm whales at 400 Hz and 2 kHz which were stable over extended periods of up to 20 mins. The clicks contained higher frequency components with energy ranging up to at least 12 kHz but not concentrated at any sharply defined frequency. The clicks of smaller female sperm whales showed similar spectral peaks, shifted to 1.2 and 3 kHz, respectively, but these peaks were less pronounced than those in the male click spectra and less stable with time. Higher frequencies were also present up to at least 15 kHz. The previously reported multiple pulse structure of sperm whale clicks is confirmed, but digital filtering reveals this structure to be frequency dependent. Analysis using the short-time Fourier transform confirms the complex time-frequency structure of individual clicks. The frequencies at which the multiples emerge in male and female clicks supports the idea of air cavities in the sperm whale head acting as sound reflectors, although the magnitude of the second pulse at high frequencies suggests some form of off axis distortion. It is also possible that air cavity resonance in the head of the sperm whale may act to reinforce the high-frequency components of the click, and that such components may have superior range and resolution performance in terms of echolocation.
在亚速尔群岛附近的深海中，记录到了来自潜水抹香鲸（包括大型雄性和较小的雌性）的规律咔哒声，随后将其采样到计算机磁盘进行数字分析。总共标记并分析了8540次咔哒声。对觅食潜水期间咔哒声间隔的简单时间分析显示，雄性抹香鲸的平均咔哒率为1.1713次/秒，雌性为1.9455次/秒。傅里叶分析表明，大型雄性抹香鲸的频谱在400赫兹和2千赫兹处有明显峰值，在长达20分钟的时间段内保持稳定。咔哒声包含频率更高的成分，能量范围至少高达12千赫兹，但并非集中在任何清晰定义的频率上。较小的雌性抹香鲸的咔哒声显示出类似的频谱峰值，分别移至1.2千赫兹和3千赫兹，但这些峰值不如雄性咔哒声频谱中的明显，且随时间稳定性较差。高频成分也至少存在于15千赫兹。先前报道的抹香鲸咔哒声的多脉冲结构得到了证实，但数字滤波显示这种结构与频率有关。使用短时傅里叶变换进行的分析证实了单个咔哒声复杂的时频结构。雄性和雌性咔哒声中多脉冲出现的频率支持了抹香鲸头部气腔充当声音反射器的观点，尽管高频处第二个脉冲的幅度表明存在某种形式的离轴失真。抹香鲸头部的气腔共振也有可能起到增强咔哒声高频成分的作用，并且这些成分在回声定位方面可能具有更好的射程和分辨率性能。
