In the turbid waters of the Kimberley, humpback whales rely on sound to navigate and communicate. Humpback whales make over 640 different “social sounds”. Male humpbacks sing complex songs, divided into phrases, sub-phrases and themes. Songs may last up to half an hour and may be repeated over hours and days. The sounds vary in frequency from 20Hz to upwards of 24 kHz. The typical range of human hearing is from 20Hz to 20kHz. The sounds vary by amplitude (loudness) or frequency (the pitch goes up and down).
The songs are only sung in the calving grounds. All males sing a similar song for the duration of a calving season, and songs are unique to individual breeding stocks, thus the west coast song is different to the east coast song. Every year there are subtle differences in the songs, and the song may evolve over the course of a season.
Humpback whales have a larynx but lack vocal chords; it is thought that they circulate air around bony structures such as cranial sinuses to produce sound.
Listen below to whale song from Camden Sound and Broome on the Kimberley coast.