Cetaceans: the new stars of vocal rhythm research

Many whale species form gregarious groups where proper communication is essential. Vocalizations can also be used to communicate aggression and mood, find food, form bonds, in threat displays, warn of intruders and coordinate movement.

Many studies have been conducted on communication in bottlenose dolphins. These animals have surprised scientists with their talents in mimicry. They have also been documented to have distinctive characteristic whistling sounds known as “signature whistles.” This whistle allows neonates to identify their mothers. Once the signature whistle of the male neonates fully develops, it will resemble that of their mother’s. Mother-calf bonds in cetaceans are essential in transmitting behaviours (culture) and in vocal learning.

It is imperative that comparative vocal rhythm research with other species be performed in parallel with vocal analysis on cetaceans. In hopes of eventually understanding how our own vocalizations have evolved, why speech has rhythm, or even how we are able to process them, we must use a comparative approach. Though there are certain similarities between species, not every aspect of speech evolved at the same time or in a similar manner. By studying the presence or absence of cognitive and behavioural traits in other species, we can determine which traits are shared between species and which ones are specific to humans.

This approach has already gained considerable momentum, and many projects comparing the vocalizations of songbirds, fish, frogs, and other mammals have already been published. Thanks to these findings, researchers were already able to conclude that isochronous vocalizations are more widespread within the animal kingdom. Most animals, like birds, frogs, primates, pinnipeds, rodents, bats, and canids are documented to produce isochronous vocalizations, especially in mating contexts or high arousals. It was also more frequently documented in territorial disputes, aggressive calls, and in instances of stress or excitement.