diacoustic

— The archbishop of Armagh (in Nᵒ 156, Philos. Trans.) compares hearing with vision; and as the latter is divided into direct, reflected, and refracted vision, so in like manner he divides the former into three parts, and considers not only direct and reflected sounds, which have been long known, but also refracted ones: for, as he observed that former ages had, in a great measure perfected the doctrine of vision by optic, catoptric, and dioptric inventions, so likewise he did not doubt, but that the doctrine of sounds, both with respect to the object, and the medium or organ, might be broutht to perfection by acoustic, catacoustic and diacoustic, or ( as he denominates them both ways ) by phonic, cataphonic, and diaphonic instruments.