Behavior

Unusual aspects of the horse’s whinny

By Modern Equine Vet News Staff

A horse’s whinny may sound like a single call, but it is a blend of both high and low frequencies (Current
Biology. 2026;36[4]: 902).

“We now finally know how the 2 fundamental frequencies that make up a whinny are produced by horses,” said Elodie Briefer, PhD, an associate professor at the University of Copenhagen. These 2 frequencies are not only important to convey different messages, they are produced through distinct mechanisms, according to Dr. Briefer.

In most large mammals, deeper voices are expected because the larynx typically grows larger with body size. But horse’s whinnies include unexpectedly high frequencies.

The low-frequency portion of the whinny comes from vocal fold vibration, much like a person singing or a cat meowing. Until now, the source of the high-frequency component was unclear. So, the team analyzed the horses’ vocal anatomy, reviewed clinical data and carried out detailed acoustic studies.

Their findings showed that the high frequency element is produced by a laryngeal whistle, similar to a human whistle, except the airflow that creates the sound becomes turbulent inside the horse’s larynx rather than at the lips. Small rodents can produce laryngeal whistles, but horses are the first large mammal identified using this method. They are also the only animals known to whistle in this way while simultaneously vibrating their vocal folds.

To confirm the source of the high-frequency sound, researchers conducted excised larynx experiments. They passed air through larynges removed from deceased horses and then alternated the airflow between normal air and helium. When helium flowed through the larynx, the high-frequency component rose in pitch, but the low-frequency component stayed the same.

These findings clarify how the 2 overlapping pitches, or biphonation, are physically produced. The researchers suggest that this vocal ability likely evolved so horses can communicate multiple independent signals at once.

They also found that Przewalski’s horses, a species closely related to domesticated horses, produce whinnies that include biphonation. However, more distant relatives such as donkeys and zebras appear to lack the high-frequency component. This difference suggests that horses developed specialized vocal adaptations, giving them a broader and more complex range of calls compared with other mammals. MeV