A previous analysis of 1977 passive acoustic recordings in the Indian Ocean focused on sound pressure levels (SPLs) and showed that SPLs were slightly depth dependent and highly influenced by shipping activities [Wagstaff and Aitkenhead, IEEE J. Ocean. Eng. 30(2), 295–302 (2005)]. Consequently, SPL alone does not provide a consistent comprehensive metric to compare among sites or with contemporary recordings in the same region. Therefore, a source separation analysis was devised and applied to identify the major sound source contributions at three Indian Ocean locations. Shipping noise was a major sound contributor in all sites, while the site with the most diverse number of sources was in the central Arabian Sea.

中文翻译：

---

1977年《重担》重新审视：对印度洋环境声源的理解

先前对1977年印度洋无源声学记录的分析集中在声压级（SPL）上，结果表明SPL随深度而变，并且受航运活动的强烈影响[Wagstaff和Aitkenhead，IEEE J. Ocean。。30（2），295-302（2005）]。因此，仅SPL并不能提供一致的综合指标来比较站点之间或与同一地区的当代唱片。因此，设计了声源分离分析并将其应用于识别印度洋三个位置的主要声源贡献。在所有站点中，运输噪声是主要的声音贡献者，而来源最多的站点位于阿拉伯海中部。