PhD Defence: Romain Lefèvre

Primary supervisor: 
Elodie F. Mandel-Briefer (KU)

Co-supervisor:
David Reby (University of Lyon/Saint-Etienne)

Assessment committee members:
David R. Nash (KU, chair), Marta Manser (University of Zurich), Livio Favaro (University of Torino)

Abstract:
Biphonation, the occurrence of two independent fundamental frequencies termed 'f0' and 'g0' in animals' vocalisations, is believed to enhance social communication. In diverse species such as amphibians, cetaceans, terrestrial mammals, or birds, biphonic calls have been proposed to captivate listeners' attention, prevent habituation, provide orientation cues, and foster group cohesion. In addition, biphonic calls act as indicators of the signaller's motivational and emotional states, as supported by variations in acoustic parameters associated with changes in the autonomic and somatic nervous systems.

This PhD project explored the biomechanisms behind the production of horses' whinnies, the function of their composing independent frequencies and the potential for combinatoriality in their structure. The outcomes of this thesis sought to contribute to a better understanding of how animals can simultaneously transmit multiple and separate pieces of information, particularly emotional content. To this end, we proposed to address the following questions:

1) What mechanisms are selectively involved in producing f0 and g0 frequencies in the horse whinnies?
2) Are these vocalisations structured in a compositional manner?
3) What roles do these distinct components play in fulfilling social communication purposes?
4) Finally, a separate project investigated if positive and negative emotional information is consistently expressed across horses and other ungulates?