Slide 48 of 127
That worked well for a long time. Writing grew more complicated, and professionals were trained to translate the writing back into language. Naturally, they read out loud.
In fact, EVERYONE read out loud. Not just the Sumerians. All through antiquity and most of the Middle Ages, everyone read out loud.
Silent reading, once you get the hang of it, is better. Easier, more efficient, nicer in the library.
Silent reading is less immersive than performance. That's just what you usually want when you read.