The chimpanzee has a voice, and vociferously expresses its
emotions.

First and most often is the plaintive, coaxing note, "Who'-oo!
who'-oo! who'-oo!"

Then comes the angry and threatening, "Wah', wah', wah-!
_Wah'_-hool _Wah'_-hool"

Lastly we hear the fearful, high-pitched yell or shriek, "Ah-h-h-
h!" or "E-e-e-e."

The shriek, or scream, can be heard half a mile, and at close
range it is literally ear-splitting. Usually it is accompanied by
violent stamping or pounding with the feet upon the floor. It may
signify rage, or nothing more than the joy of living, and of
having a place in which to yell. It is this cry that is uncannily
human-like in sound, and when heard for the first time it seems to
register anguish.

In its Bornean jungle home, the orang-utan is nearly as silent as
the grave. Never save once did I hear one utter a vocal sound.
That was a deep bass roar emitted by an old male that I disturbed
while he was sleeping on the comfortable nest of green branches
that he had built for himself.

Concerning the chimpanzee, the late Mr. Richard L. Garner
testified as follows: