厦门海域中华白海豚定位click信号特性

对厦门海域中华白海豚的发声及信号特性进行研究,采用高频宽带数据记录系统获取了大量中华白海豚click信号,并利用Matlab软件和Excel 2007对这些信号进行时域和频域分析.结果表明:click信号通常以不同长度的序列形式出现,单个click信号长度分布在(33±4)μs;频谱能量分布广,低频至10kHz,高频达200kHz以上,具有单峰和双峰2种频谱结构,峰值频率、3dB带宽和10dB带宽分别为(113.3±16.3)、(48.3±14.2)和(113.3±16.4)kHz.中华白海豚click信号双峰的频率分布,为其在海底混响严重的浅海环境准确识别目标提供了保障.

Study on the Characteristics of Echolocation Clicks from Indo-Pacific Humpback Dolphins(Sousa chinensis) in Xiamen

The vocalizations and signal characteristics of humpback dolphins(Sousa chinensis) in Xiamen were studied in this paper.A large number of original click signals were obtained by a broad frequency-band recording system.These signals were analysed as waveforms and spectrograms using Matlab tool and Excel 2007.Results of this study indicate that clicks of humpback dolphins occur as trains.The duration of each click trains vary wildly,ranging from a few seconds to tens of seconds,but single click have a short duration around(33±4) μs.The echolocation clicks have a wide range of frequency distribution between 10 kHz and 200 kHz.Click signals have two types of spectrum structure and have an averaged peak frequency of(113.3±16.3) kHz with 3 dB bandwidth of(48.3±14.2) kHz.The 10 dB bandwidth of(113.3±16.4) kHz is also given in the results.Most of the echolocation clicks have a bimodal frequency distribution,which provides a good range resolution capability that should enable dolphins to be able to perform fine target discrimination in a shallow water environment where bottom reverberation can be troublesome.