In Gbaya, the notion of the light and suspended fringe in Numbers 15:38 is emphasized with mbɛlɛ-mbɛlɛ, an ideophone used to describe something light that is suspended, such as a tassel.
Ideophones are a class of sound symbolic words expressing human sensation that are used as literary devices in many African languages. (Source: Philip Noss)
See also fringe / tzitzvit and their fringes long.