It is used to describe someone cackling: "laughing
like a hyena."
Scientists who have
studied hyenas will tell you the unique sounds they make are not
actually laughing. Hyenas do indeed make loud barking noises
that sound like cackling laughter, but it is not because they
are amused by anything.
Instead, a hyena's
sound is actually a form of communication used to convey
frustration, excitement, warning, or fear. Most often, you hear
this unique vocalization during a hunt or when the animals are
feeding on prey as a group.
What sounds like
maniacal giggling to humans lets other hyenas know that one of
the other members of their pack has either made a kill or been
attacked. When sharing a fresh kill, the sound might also
indicate frustration on the part of a younger animal that did
not get its fair share yet. Likewise, the animal in possession
of the meat might also 'laugh' as a warning to others that it is
not ready to share yet.
There are several
species of hyenas, and they all have a variety of unique
vocalizations. Only one of these species, the spotted hyena
makes the laughing sound that has become synonymous with hyenas,
in general.
Researchers have also
learned that the pitch of a hyena's sound usually varies
dependent upon its social status. Hyena packs are matrilineal,
which means that females are dominant and lead the pack. There
is intense competition for food within a pack, and the
subordinate animals, often male tend to make the sound more
frequently with a higher pitch.