The waves are just an array of points that with some raycasting and stuff reflect from the walls and reveal those walls.
But the reason the echolocation was ditched is that (spoiler alert) the sun was revealed so does the light, basically, you can now see the world and there was no reason to use abstract shapes and echolocation. I agree that probably I should've used the echolocation at the end in some way, but I wanted to create a "WHAT?" effect on the player and disorient them. And I think I did it??