Just two years ago, the world went into a frenzy trying to figure out What does the fox say? Meanwhile, another silent creature, the giraffe, remained mostly ignored. Researchers have finally gotten around to recording the animal and, apparently, they hum. Observing the giraffes over an eight-year period and capturing 940 hours of sounds, the researchers have finally concluded thataside from the occasional gruntgiraffes produce an incredibly low (yet audible) 92Hz hum to communicate with each other. However, they only hum at night.