1) Vocal skill 
Eefing (also written eeephing, eephing, eeefing, eefin, or eefn`) is an Appalachian (United States) vocal technique similar to beatboxing, but nearly a century older. Jennifer Sharpe describes it as `a kind of hiccupping, rhythmic wheeze that started in rural Tennessee more than 100 years ago.` An eefing piece called `Swamp Root` was one of t...