Here are some possible ways to pronounce it:
* "NAR-bul": This pronunciation emphasizes the "nar" sound, similar to "gnarled" or "gnarly."
* "GAR-bul": This pronunciation emphasizes the "gar" sound, similar to "garble" or "gargoyle."
* "NARB-ul": This pronunciation emphasizes the "arb" sound, similar to "arboreal" or "arbor."
Ultimately, the best way to pronounce "gnarble" would be to check the context in which it's used. If it's part of a fictional language or a specific work, the author might provide guidance on its pronunciation. Otherwise, you can use whichever pronunciation feels most natural to you.