In stories he wrote in the 1920s and 1930s, H. P. Lovecraft used the word meep to
represent the vocalizations made by ghouls. Lovecraftian ghouls were subterranean humans that had degenerated into dog-like
cannibalistic creatures.
A man he had known in Boston ... had actually made friends with the ghouls and had taught him to
understand the simpler part of their
disgusting meeping and
glibbering." ~ in "The Dream Quest of Unknown Kadath"