the drum depicts a microcosm with its three zones—sky, earth, underworld—at the same time that it indicates the means by which the shaman accomplishes the break-through from plane to plane
Eliade establishes the drum as a cosmological instrument whose iconography enacts the shaman's axis mundi passage, making it the definitive vehicle of ecstatic inter-planar travel.
, Shamanism: Archaic Techniques of Ecstasy, 1951thesis