In Gbaya, the notion of deep darkness is emphasized in the referenced verses with kpɔ̧ɔ̧-kpɔ̧ɔ̧, an ideophone that refers to something very black, dark black like the darkness of night the movement or motion of shaking.
Ideophones are a class of sound symbolic words expressing human sensation that are used as literary devices in many African languages. (Source: Philip Noss)