Bioacoustic research on voice production reveals similarities between toothed whales and humans
Voice production in toothed whales - which also include dolphins - follows a similar physical mechanism as in humans. This is the result of a recent study: Biophysicist and voice researcher Christian Herbst from the Department of Behavioral and Cognitive Biology at the University of Vienna comments on the results of this work in the renowned journal Science and emphasizes how important combined research approaches are in order to understand the acoustic world around us.
Toothed whales use their voice to communicate with conspecifics and also as a biosonar to navigate the oceans and find food. A recent paper by Madsen et al. published in Science now shows for the first time in detail how the vocal sounds required for this are produced in the animals’ nasal passages. Surprisingly, the physical mechanism for voice production in toothed whales is similar to that in humans and other mammals - even though their vocal organ is not located in the throat but in the nose.
Christian Herbst and his colleague Andrea Ravignani from the Max Planck Institute for Psycholinguistics in Nijmegen (NL) discuss the specificity of this evolutionary development in their commentary. "In humans and almost all other mammals, the vocal sound is produced by cyclic oscillation of tissues," Herbst explains. In this process, the aerodynamic energy of vocal exhalation is converted into acoustic energy. From the point of view of evolutionary strategy, this physical mechanism is so successful that the vocal apparatuses of different animals have been able to develop in different localizations in the body: in humans and mammals in the throat (larynx), in birds in the thoracic cavity (syrinx) and - as currently described - in toothed whales in the nose.
Interestingly, there are even further convergent developments in the voice production of toothed whales and humans: The three mechanisms of voice production described in the study are physically very similar to the so-called vocal registers in humans. These vocal registers - such as "chest voice" or "head voice", among others - are important in speech as well as in singing and can be easily perceived as different, for example, when yodeling or when boys accidentally "squeak" their voice when their voice breaks. Toothed whales thus possess, in principle, similarly diverse vocal production abilities as humans. "It is impressive that many mammals have physically comparable vocal capabilities to humans and use them appropriately in non-verbal communication," Herbst says. "But the fact that we can use the voice beyond that to sing opera or heavy metal, for example, makes us unique in the animal kingdom."
Publication in Science:
Andrea Ravignani, Christian T. Herbst: Voices in the ocean. Science, 2023.