Long-term data of underwater passive acoustic monitoring (PAM) collected from two sites of pygmy blue whale presence within Australia, the continental shelf off Portland (38.5° S, 141.2° E) and the Perth Canyon (32° S, 115° E) were analysed to compare the acoustic behaviour of eastern Indian Ocean pygmy blue (EIOPB) whales. Pygmy blue whale song detection was consistently higher at the Perth Canyon site than at the Portland sample site. Statistical analysis found there to be a significant difference in the production of song and phrase variants between sites (p < 0.01) with a shorter two-unit (P2) song variant being more common in the Perth Canyon area, while the traditional three-unit (P3) song variant was more frequent off Portland. This was supported by manual and feature space analysis techniques. Increasing song complexity was observed in the form of phrases with broken song units, a phenomenon that was first observed at the Portland site on isolated occasions but has occurred and proliferated in the Perth Canyon area from 2016 onwards. Analysis of environmental conditions indicated that increased background noise due to multiple EIOPB whales vocalising, as well as water depth, may influence song length. This was reflected by songs made up of shorter phrases dominating in higher background noise conditions and deeper water, while longer more complex phrase types dominate in quieter, shallower conditions. Further research is recommended to isolate any potential influence of environmental factors on song production.

水下无源声监测（PAM）的长期数据是从澳大利亚境内的侏儒蓝鲸存在的两个地点收集的，波特兰附近的大陆架（38.5°S，141.2°E）和珀斯峡谷（32°S，115°E进行了分析，以比较印度洋东部矮小蓝鲸（EIOPB）鲸的声学行为。珀斯峡谷地点的侏儒蓝鲸歌曲检测始终高于波特兰样本站点。统计分析发现，网站之间的歌曲和乐句变体的产生存在显着差异（p <0.01），而在珀斯峡谷地区，较短的两单元（P2）歌曲变体更为常见，而在波特兰以外，传统的三单元（P3）歌曲变体则更为常见。手动和特征空间分析技术对此提供了支持。歌声的复杂性以歌声破碎的短语形式出现，这是一种现象，这种现象首次在波特兰站点被单独观察到，但从2016年开始在珀斯峡谷地区发生并扩散。对环境条件的分析表明，由于多次EIOPB鲸发声而引起的背景噪音增加以及水深可能影响歌曲的长度。这反映在歌曲中，这些歌曲是由较短的短语构成的，在较高的背景噪音条件下和较深的水里占主导地位，而较长的较复杂的短语类型则在较安静的环境中占主导地位，较浅的条件。建议进行进一步的研究，以隔离环境因素对歌曲制作的任何潜在影响。