Sub-unit classification of Pacific and Atlantic humpback high-complexity song units—Sub-unit diversity drives unit diversity

Abstract

Humpback whale communication studies have primarily focused on holistic unit classification methods to identify thematic patterns of song structure. These various whole-unit, spectral-feature-extraction and classification procedures have resulted in low information entropy estimates of songs, akin to bird song. A recent study of high complexity, frequency-modulated song units shows that unit diversity and information entropy of humpback vocalizations is much higher and variable across regions of the Pacific and the Atlantic. Sub-unit-level feature-extraction and classification of these high-complexity units indicates that humpbacks have precision control of the generation of target frequencies, a characteristic of human vowel production. The number of distinct sub-units varies by geographic region and is comparable to English and Asian language phoneme sets.