The study, made by scientists from the University of Vienna and Berlin Tierpark in Germany and published in BioMed Central Journal, explains how researchers recorded the sounds giraffes from three European zoos make over a period of 8 years, gathering 947 hours. Although it was believed that they emit sounds which are imperceptible for the human ear, it seems that their ’hum’ has a frequency of 92Hz, slightly hearable by human beings.
In the past, scientists even suggested that giraffes use infrasonic sounds that could not be heard by humans.
The researchers noticed that this humming occurs only at night. They couldn’t establish if this sound represents a way of communicating with other giraffes or just a passive sound while sleeping.
“Giraffes do produce vocalizations, which based on their acoustic structure, might have the potential of function as communicative signals,” the researchers say.
Despite having well-developed larynx, it was believed that because of the long neck, giraffes are not capable of producing enough air-flow in order to emit sounds. But it seems that the new research shows something else.
Analyzing the relation between vocal cords and nose production, they concluded that the humming sound comes from the right place and is stronger than it was believed.
Trying to justify the reason why giraffes emit those sounds during night, the scientists believe that the reason is their less sharp vision, otherwise very keen.
Although experts believe that their research requires a stimulating interest, time and is tiresome by reason of length, they do believe that this work must be continued in order to find out the reason giraffes hum at night and to offer an insight into their social behavior.
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