Often melodious voices would be associated with music, and pleasurable ones from a sultry nature.
But there is a sort of voice that fulfills both for me, that neither fits the musical nor sultry box. Closest I could get of a descriptor is a gentle, quiet confidence. And almost like a sensory experience, because if one could smell it, delicate sweetness would be its scent.
It has the ability to caress my heart, and drown me.