A: Despite the heavy use of moaning Zombies in both print and film, the fact is that most Zombies are incapable of moaning at all.
The idea of the moaning Zombie originated with the victims of premature burial. Before the 1900s many places around the world would bury their “dead” as soon as possible, this was often due to the fact that many doctors were under-trained and medical technology still had a long way to go. Premature burials have claimed many victims, and these victims cries for help could often be heard coming muffled from the grave. While the number of premature burials have dropped drastically worldwide, they still remain a frightening occurrence, even in the most sophisticated of places.
Voodoo Zombies suffer great mental strain during their time in the grave and throughout their metamorphosis; which often leaves them stricken of their ability to speak, leaving them with mumbles and moans for communication, but remember that this type of Zombie is not the undead. And although Type II Viral Zombies are capable of moaning, they are more apt to scream, yell, snarl, and make more aggressive noises than moaning.
Did you know that the sound of a moan comes from air passing up and past the vocal chords and through the mouth or nose? Because undead Zombies, like Type I Viral and Chemical Zombies, don’t actively breath and take in air, they just aren’t capable of truly moaning. But the gases escaping their bodies do a pretty good job of emulating the eerie sound we have all come to know as “The Zombie moan“.