Researchers have discovered that horses produce two distinct sounds simultaneously when they whinny [1].

This finding changes the scientific understanding of mammalian vocalization. It provides the first experimental proof that a mammal can combine a high-pitched whistle with low-frequency vibrations in one call, a capability previously undocumented in the animal kingdom.

The study, published Feb. 23, 2026 [2], explains the mechanics behind the distinctive equine call. Scientists found that the whinny consists of two components [1]. One is a high-pitched whistle generated by the mouth, and the other is a low-frequency tone created by the vibration of the vocal folds.

For years, the exact method horses used to generate this sound remained a mystery. By isolating these two frequencies, researchers were able to demonstrate how the animal coordinates different parts of its vocal tract to create a complex acoustic signal.

"Horses have a vocal trick no one fully understood until now," ScienceDaily said [1].

The research focused on the physical production of the sound to explain how these simultaneous frequencies are possible. The ability to layer a whistle over a vocal-fold tone allows the horse to produce a call that is both piercing and resonant, characteristics that may aid in long-distance communication within a herd.

This experimental evidence marks a shift in how biologists categorize mammalian sounds. While many animals can whistle or hum, the simultaneous execution of both mechanisms in a single breath is a rare physiological feat.

“Horses produce two different sounds at the same time when they whinny.”

This discovery challenges existing models of mammalian anatomy and vocal capabilities. By proving that horses can utilize two different sound-production mechanisms at once, the study suggests that mammalian vocal tracts may be more versatile than previously thought, potentially opening new avenues for research into the evolution of communication across other species.