Giraffes don’t
communicate, but they can hum a song. University of Vienna scientists listened
to 1,000 hours of sound recording of giraffes in three European zoos. They
found no evidence of infrasonic communication.
Scientists previously
thought that giraffes could not make any ‘substantial’ sounds because of their
long necks (New Scientist, September 17, 2015). They thought it was physically
impossible for giraffes to generate sufficient air flow through their long
necks to produce vocalisations. Other scientists thought that giraffes produce
low frequency ‘infrasonic’ sounds – that humans cannot hear – to communicate to
each other. Now scientists listening to the recorded sounds of giraffes in
three zoos found that they don’t communicate but they emit a ‘weird humming at
night.’
Angela Stoger of the
University of Vienna in Austria said the humming sounds have a ‘complex
acoustic structure.’ The low frequency sound of about 92 Hz is not infrasound
because humans can hear it. The research team said they heard the giraffe
sounds, which varies in duration and contains ‘a rich combination of notes.’
The humming, which
occurs only at night, could be ‘passively produced’ – similar to snoring or
produced during a dream-like state. Or it could be a method for communicating
in the dark when vision is limited.
Residents in Paignton
in southwest England complained last year of ‘humming or droning noises coming
from the giraffe house’ at the nearby Paignton Zoo. However the zoo says the
giraffes weren’t involved in the experiment. Researchers think the residents
may not have heard the humming because the signals are not ‘intensive’ –
giraffes hum quietly. However, if there are several giraffes, well maybe …
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