Small explosive charges, called seal bombs, used by commercial fisheries to deter marine mammals from depredation and accidental bycatch during fishing operations, produce high level sounds that may negatively impact nearby animals. Seal bombs were exploded underwater and recorded at various ranges with a calibrated hydrophone to characterize the pulse waveforms and to provide appropriate propagation loss models for source level (SL) estimates. Waveform refraction became important at about 1500 m slant range with approximately spherical spreading losses observed at shorter ranges. The SL for seal bombs was estimated to be 233 dB re 1 μPa m; however, for impulses such as explosions, better metrics integrate over the pulse duration, accounting for the total energy in the pulse, including source pressure impulse, estimated as 193 Pa m s, and sound exposure source level, estimated as 197 dB re 1 μPa² m² s over a 2 ms window. Accounting for the whole 100 ms waveform, including the bubble pulses and sea surface reflections, sound exposure source level was 203 dB re 1 μPa² m² s. Furthermore, integrating the energy over an entire event period of multiple explosions (i.e., cumulative sound exposure level) should be considered when evaluating impact.

中文翻译：

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封印炸弹爆炸声源表征

小型炸药，称为海豹炸弹，被商业渔业用于阻止海洋哺乳动物在捕鱼作业期间遭到掠夺和意外误捕，会产生高强度的声音，可能会对附近的动物产生负面影响。海豹炸弹在水下爆炸并用校准的水听器在不同范围内进行记录，以表征脉冲波形并为源级 (SL) 估计提供适当的传播损耗模型。波形折射在大约 1500 m 的倾斜范围内变得重要，在更短的范围内观察到近似球形的传播损失。密封炸弹的 SL 估计为 233 dB re 1 μPa m；然而，对于爆炸等脉冲，更好的指标在脉冲持续时间内积分，考虑到脉冲中的总能量，包括源压力脉冲，估计为 193 Pa ms，² m ² s 超过 2 ms 窗口。考虑到整个 100 ms 波形，包括气泡脉冲和海面反射，声源水平为 203 dB re 1 μPa ² m ² s。此外，在评估影响时，应考虑对多次爆炸的整个事件期间的能量进行积分（即累积声暴露水平）。