One of a number of Galouye SF novels focusing on some form of perception, Dark Universe is told from the viewpoint of Jared Fenton, a young man and skilled hunter of "soubats", in a tribe called the Survivors living in the "Lower Level" - what is evidently the depths of a cave system. Light having been forgotten except in name, the Survivors find their way about using echos: by a central "echo-caster" in their main dwelling area, and by rattling "clickstones" elsewhere. Their sense of smell is also well-developed. Jared has various problems - a forthcoming arranged marriage, his tribe's dwindling resources, and the incursion of foul-smelling wrinkly-skinned monsters that bring "screaming silent sound" - that lead him into an exploration, first meeting "zivvers" (humans who have evolved to see infrared), and finally the worldview-shaking reality that the monsters are clothed people from the outside world bringing light. There's a strong allusion to Plato's Parable of the Cave.
From a perceptual standpoint, the end of Dark Universe, when Jared emerges from the caves and adapts to his newly-discovered sense of sight, is unfortunately nonsense. It's now known - Google Wiesel and Hubel if you must - that if eyes aren't exposed to visual input at a formative age, the neural equipment to process it won't work. But the story is so well told and the details so well worked out, right down to the bureaucracy and ritual (among the Survivors, the "Misplacement of Bulky Objects" is a crime on a par with murder) that it's easy to suspend disbelief. I've mentioned other Galouye works in a previous post, PK Dick, Ubik and conceptual breakthrough.