Watch VoirFilms. Mouth Music demonstrates the distinctive modes of the human voice, the most influential of all musical instruments, takes on in southern folk music and folk culture. These modes can span traditional a cappella performance styles as well as unique expressive vocal forms that have evolved as part of daily life, work, and play: hollerin’, jump-rope rhymes, “eephing,” nonsense songs, auctioneering, drill sergeant’s patter and others.