The asson is a sacred rattle used by houngan and mambo, Haitian Vodou priests and priestesses, made from a hollowed gourd covered in a woven net of beads and, distinctively, small snake vertebrae, and shaken during ceremonies specifically to help call and communicate with the lwa, the spirits central to Vodou practice. Brown's ethnography of Vodou practice, developed through extended fieldwork with a practising mambo, describes the asson as functioning as far more than a musical accompaniment to ritual song and dance; its sound is understood within the tradition as part of the technical means by which a priest actively directs and structures a ceremony's communication with the spirit world, comparable in seriousness to how a ritual object functions in other traditions where a specific implement is treated as inseparable from the officiant's recognised authority to perform the rite at all.
Receiving one's own asson marks a specific, formally recognised threshold in Vodou priesthood, and a practitioner who has been through this initiation is described as asogwe, distinguishing a fully initiated priest or priestess from other, less formally elevated ranks of Vodou religious practice. Vodou temples, or peristyles, generally keep more than one asson on hand for use by different serving priests, and the instruments themselves are sometimes ritually fed or refreshed periodically, a form of ongoing care that treats the object as a living working tool rather than a static piece of equipment.