Many animals increase the intensity of their vocalizations in increased noise. This response is known as the Lombard effect. While some previous studies about cetaceans report a 1 dB increase in the source level (SL) for every dB increase in the background noise level (NL), more recent data have not supported this compensation ability. The purpose of this study was to calculate the SLs of humpback whale song units recorded off Hawaii and test for a relationship between these SLs and background NLs. Opportunistic recordings during 2012–2017 were used to detect and track 524 humpback whale encounters comprised of 83 974 units on the U.S. Navy's Pacific Missile Range Facility hydrophones. Received levels were added to their estimated transmission losses to calculate SLs. Humpback whale song units had a median SL of 173 dB $\text{re}\hspace{0.17em}1\hspace{0.17em}\mu \text{Pa}$ at 1 m, and SLs increased by 0.53 dB/1 dB increase in background NLs. These changes occurred in real time on hourly and daily time scales. Increases in ambient noise could reduce male humpback whale communication space in the important breeding area off Hawaii. Since these vocalization changes may be dependent on location or behavioral state, more work is needed at other locations and with other species.

中文翻译：

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座头鲸唱歌中的伦巴第效应：随着海洋环境噪声水平的增加，源头水平也随之增加。

许多动物会通过增加噪音来增强发声的强度。这种反应称为伦巴第效应。尽管先前有关鲸类动物的一些研究报告说，背景噪声电平（NL）的每增加1 dB，源电平（SL）就会增加1 dB，但是最近的数据还不支持这种补偿能力。这项研究的目的是计算在夏威夷附近记录的座头鲸歌曲单位的SL，并测试这些SL与背景NL之间的关系。2012-2017年期间的机会性录音用于检测和跟踪524座座头鲸遭遇，其中包括美国海军太平洋导弹靶场设施水听器上的83974单位。将接收到的电平添加到其估计的传输损耗中以计算SL。座头鲸鲸鱼歌曲的中位SL为173 dB$\text{回覆}\hspace{0.17em}\mathrm{1个}\hspace{0.17em}\mu \text{帕}$在1 m处，SL的背景NLs增加了0.53 dB / 1 dB。这些更改按小时和每日时间范围实时发生。环境噪声的增加会减少夏威夷外重要繁殖区的雄性座头鲸交流空间。由于这些发声变化可能取决于位置或行为状态，因此需要在其他位置和其他物种进行更多工作。