Onomatopoeia is the formation of a word from a sound associated with what it is named. Examples include:
* Buzz (like a bee)
* Meow (like a cat)
* Bang (like a gunshot)
While "hollering" describes a loud shout, it doesn't mimic the sound itself.
However, you could use "hollering" in an onomatopoeic sentence like:
* "He let out a loud 'HOLLER' that echoed through the valley."
In this case, the word "HOLLER" is written in all caps to mimic the sound of a shout.