Another trick that Planet Zoo's team employed was playing up some of the smaller sounds that animals make: Little grunts, breaths, and other things you would likely never be close enough to hear. "Ironically, this makes them sound more realistic as this is what the player would expect," says audio designer Ben Scholey.
In these instances, human sounds can fill in the gaps that sound libraries can't. "The breaths of the tortoise, for example, is the sound of breathing through a hose, and some of the juvenile big cat grunts were a fellow human being in the recording booth."
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