Blue whales were heavily exploited throughout the early 20th century, with many populations hunted to near extinction. Today, a number of known sub-populations of blue whale exist, separated by geographic range and the acoustic signals they produce. The eastern Indian Ocean sub-population of pygmy blue whales is easily identified by the production of a characteristic Australian song type. Passive acoustic monitoring in the Perth Canyon, Western Australia, has allowed for long term collection of sea noise data. Analysis of individual call detections has revealed several variations to the traditional three-part Australian blue whale song type. These variations include six different song structures and two variants to the three-part song type in the form of changes to the inter-song interval. Changes to song structure are achieved through the shortening of the three-part song by the loss of components, or the combination of multiple structures into hybrid song types. All six song variants have been recorded within one year, indicating that high levels of song diversity may be attributed to individual animals producing song variants rather than population-wide processes. The mechanisms behind variability in song production are unclear though there is research to suggest that changes to vocal behaviour may be culturally driven or caused by changes in ambient noise conditions. Anthropogenic noise production by a growing industrial sector is of increasing concern for populations such as the Eastern Indian Ocean pygmy blue whale whose migratory corridors overlap with areas of importance for the shipping and mining industries.