Banganga (meaning diviners; literally 'masters / priests of minkisi') defend community members against illness, witchcraft, infertility, and can even provide success in specific pursuits like hunting, by leveraging minkisi figures. In addition to nkisi figures, another tool used by banganga diviners is the nsiba divination whistle.
A combination of the Vili word nsia, a species of antelope (Silvicapa), and the verb siba, meaning 'to call on a nkisi', nsiba whistles are used to awaken and call upon the ancestral spirits (bakulu) residing within minkisi figures. Blowing into the the wide opening of the antelope horn, the nganga invokes the nkisi into defending his client against witchcraft and protecting them against diseases and misfortune.
Nsiba whistles also function as hunting charms. Worn by chiefs and prominent hunters, they are used to communicate with each other during group hunts and also to subdue and cast spells over game. "These activities complement each other metaphorically—just as a hunter stalks his prey, so does a diviner track down criminals, sorcerers, and other sources of illness, death, and suffering".4
Two components make up vertical whistle: