When you hear a horse whinny, you probably recognize it instantly. But did you know that researchers were puzzled about how horses produced some of these sounds until recently? Elodie Floriane Mandel-Briefer, a biologist at Copenhagen University, led an interdisciplinary study that unveiled the mystery behind these whinnies.
About 10 years ago, Mandel-Briefer and her team discovered that horses produce two pitches that create a vocal phenomenon called biphonation. The low-frequency component results from vibrations of the vocal folds, similar to how humans and most mammals produce sound. However, the high-frequency part was a mystery due to the large size of horses.
Through their study published in the journal Current Biology, the researchers found that a laryngeal whistle in horses’ throats is responsible for the high-frequency whinny component. By blowing air through horse larynges, they demonstrated how horses create these distinct sounds.
Furthermore, the team found that horses combine vocal fold vibration and laryngeal whistling to create biphonation, a unique feature among animals. This discovery sheds light on how horses communicate complex messages through their vocalizations.
Interestingly, the study also revealed that the frequency and emotion in a horse’s whinny are interconnected. The high-frequency component indicates the horse’s emotional state, while the low-frequency component represents the intensity of that feeling. This dual vocal mechanism allows horses to communicate effectively over long distances.
While other equids like zebras and donkeys do not have the high-frequency part in their vocalizations, Przewalski’s horses, closely related to domesticated horses, also exhibit biphonation. This suggests that horses have evolved distinctive vocal adaptations for communication.
Overall, this research highlights the fascinating adaptability of the mammalian vocal production system, providing valuable insights into horses’ cognition, emotions, and welfare. Understanding the communication system of horses can lead to a better understanding of these majestic animals and their unique vocal abilities.
