Whistle while you whinny: researchers identify two sounds straight from the horse's mouth

Nature

by Katherine Bourzac

February 23, 2026

AI-Generated Deep Dive Summary

Horses have long been known for their distinctive whinny, a sound that plays a crucial role in their social interactions. However, new research reveals an extraordinary aspect of horse communication: they produce two distinct sounds simultaneously. This dual-frequency vocalization involves a low-frequency "nickering" from their vocal folds and a high-pitched whistle created by air passing through the cartilage of their larynx, a phenomenon known as biphonation. This ability allows horses to convey complex emotions and messages, such as excitement or stress, to other horses. The study, conducted by Elodie Briefer and her team at the University of Copenhagen, used advanced imaging techniques like endoscopy to observe horse vocal folds in action. They also performed experiments with horse larynges, including introducing helium into the air passed through the larynx to determine how sound frequencies change. This revealed that the high-frequency whistle is not caused by vibrating tissues but rather by airflow through a tube-like structure, while the low-frequency sound originates from vocal fold vibrations. This discovery places horses in an exclusive club of creatures capable of biphonic sounds, joining birds, human beat boxers, and throat singers like Mongolian performers. The research highlights how horse vocalizations are far more intricate than previously understood, with each horse having a unique whinny that reflects its emotional state. This insight not only deepens our understanding of animal communication but also underscores the complexity of vocal mechanisms across species. The findings matter because they challenge previous assumptions about horse vocalization and expand our knowledge of animal behavior and bioacoustics. By unraveling how horses produce such complex sounds, researchers open new avenues for studying animal communication and emotional expression. This work could have implications for fields ranging from comparative biology to animal welfare, offering fresh perspectives on how animals interact with each other and their environment.

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Originally published on Nature on 2/23/2026