Biomechanical Breakthrough: Scientists Reveal How Horses "Sing and Whistle" Simultaneously

Scientists solve the mystery of the horse whinny, discovering that horses produce two sounds at once using vocal fold vibrations and a unique laryngeal whistle.

By: AXL Media

Published: Feb 25, 2026, 5:54 AM EST

Source: The information in this article was sourced from Cell Press

The Mechanics of the Dual-Tone Whinny For centuries, the horse's whinny was heard as a single, complex sound, but researchers from the University of Copenhagen and the University of Vienna have deconstructed it into two independent components. The lower frequency is produced through the standard vibration of vocal folds, similar to human speech. However, the high-pitched "scream" that accompanies it is actually a laryngeal whistle, where turbulent airflow inside the larynx creates a sound independent of the vocal folds.

A First for Large Mammals While small rodents like mice are known to use laryngeal whistles, horses are the first large mammals confirmed to possess this capability. This discovery challenges the traditional understanding of mammalian acoustics, which typically dictates that larger animals produce lower-pitched sounds due to their larger larynges. Horses bypass this biological constraint, allowing them to produce high-frequency calls that carry across long distances and convey nuanced social information.

Confirming the Mystery with Helium To prove the existence of the laryngeal whistle, the research team conducted "excised larynx" experiments using helium. Because sound travels faster in helium, any frequency generated by air turbulence (a whistle) will shift in pitch, while sounds generated by physical vibrations (vocal folds) remain stable. When helium was passed through the horse larynx, the high-pitched component spiked while the low-pitched tone stayed the same, providing definitive proof of the two distinct mechanical origins.

Evolutionary Advantage of Biphonation The ability to produce two sounds at once—biphonation—likely evolved to allow horses to encode more complex information. According to lead author Elodie Briefer, these two frequencies convey different messages about the horse's emotional state. By "layering" these sounds, a horse can communicate its identity, emotional intensity, and social intent simultaneously, providing a survival advantage in the wild where clear communication within the herd is vital.

Comparative Vocal Diversity The study also looked at the horse’s closest relatives to trace the evolution of this trait. While the endangered Przewalski's horse also exhibits biphonation, more distant relatives like donkeys and zebras lack the high-frequency whistle component. This suggests that the specialized vocal ana...