Giraffes are known to produce low-frequency vocalizations described as hums.
For many years, giraffes were often portrayed as nearly silent because people rarely heard them calling. Research and recordings later showed that giraffes can produce several sounds, including moos, snorts, coughs and low-frequency humming, particularly at night.
The nighttime hum is low enough to be easily overlooked by people and may help maintain social contact when visual conditions are poor. Scientists continue to investigate exactly how often it is used and what information it carries. A low pitch does not automatically mean that a sound is infrasonic; “hum” is the commonly reported description, while the frequency range depends on the recording and study.
Giraffes also communicate visually and chemically. Their posture, movement and proximity convey social information, while urine and other odors may provide clues about reproductive condition. Thus, the idea that giraffes make no sounds is an oversimplification, not a reliable biological fact.