Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii 96744, USA.
SEAMARCO (Sea Mammal Research Company), Julianalaan 46, 3843 CC Harderwijk, The Netherlands.
J Acoust Soc Am. 2019 Oct;146(4):2475. doi: 10.1121/1.5128328.
Acoustic backscatter measurements were conducted on a stationary harbor porpoise (Phocoena phocoena) under controlled conditions. The measurements were made with the porpoise in the broadside aspect using three different types of signals: (1) a 475 μs linear frequency-modulated (FM) pulse with a frequency range from 23 to 160 kHz; (2) a simulated bottlenose dolphin (Tursiops "truncates") click with a peak frequency of 120 kHz; and (3) a simulated killer whale (Orcinus orca) click with a peak frequency of 60 kHz. The measurement with the FM pulse indicated that the mean target strength at the broadside aspect decreased from -26 to -50 dB as the frequency increased from 23 to 120 kHz in a nearly linear fashion (on a logarithm plot). Target strength variation with frequency was similar to a previous backscatter measurement on a bottlenose dolphin over a comparable frequency range (23-80 kHz). The porpoise seems to be a stealth body with low backscatter properties. The target strength of the porpoise was also about 15-16 dB lower than that of the bottlenose dolphin. The difference in lung volume of the two species when expressed in dB was also approximately 15 dB.
在受控条件下，对静止状态下的港豚（Phocoena phocoena）进行了反向散射测量。使用三种不同类型的信号（1）具有 23 至 160 kHz 频率范围的 475 μs 线性调频（FM）脉冲；（2）模拟宽吻海豚（Tursiops "truncates"）的咔嗒声，峰值频率为 120 kHz；以及（3）模拟虎鲸（Orcinus orca）的咔嗒声，峰值频率为 60 kHz，对豚侧进行了测量。FM 脉冲的测量结果表明，在从 23 kHz 到 120 kHz 的近乎线性的频率范围内，豚的平均目标强度从-26 dB 降低到-50 dB（在对数图上）。与频率的目标强度变化与在类似频率范围内（23-80 kHz）对宽吻海豚进行的先前反向散射测量相似。海豚似乎是一种具有低反向散射特性的隐形体。海豚的目标强度也比宽吻海豚低约 15-16 dB。当以 dB 表示时，两个物种的肺容量差异也约为 15 dB。
