Scientists at the Zurich’s Federal Institute of Technology ETHZ have identified two different frequencies in a horse’s whinny that can indicate emotional state and level of excitement. This could help in providing better care.
Whinnies are the longest, loudest and most common horse communication and are composed of three parts: introduction, climax and end. But until now, it was not known that horses could whinny in two “voices”.
“One frequency indicates whether the emotion is positive or negative, while the other frequency reveals the strength of the emotion,” says project leader Elodie Briefer, of ETHZ’s Ethology and Animal Welfare Unit.
The researchers were able to associate positive emotions with short whinnies in which the higher frequency was lower, accompanied by a lowering of the head. When expressing negative emotions the whinnies were longer and the higher frequency was higher.
Scientists do not yet know how horses produce such complex sounds simultaneously. They suspect that the two different frequencies are a result of an “asynchronous vibration pattern of the vocal cords”.
The research team analysed 267 whinnies collected from 18 different horses to arrive at the conclusion. Cameras and microphones were used to capture horse behaviour and sounds. Physiological responses, such as heart rate, breathing and skin temperature were also recorded. To correlate the sounds and behaviour produced with positive or negative emotions, the horses were separated or united with their herd.
The researchers expect that the results of the study will help horse owners and veterinarians to respond better to horses’ needs.