Noah couldn't see the changes in the Pyramid because he was running as fast as he could toward the exit. Still, the guards outside the structure could inspect the events through the sensors previously placed by the experts of the Balrow family.
Chief Etta and the guards had seen that Noah had succeeded in entering some protected areas. Their interest in him had skyrocketed at that point. They couldn't let such a powerful and talented inscription master escape from their clutches.
Still, they forgot about Noah when the Pyramid began to tremble. Their sensors sent signals that they couldn't completely understand. It was as if the whole structure had taken life after Noah cleared the secret room in the first layer.
The guards saw how a massive amount of energy flowed toward the top of the Pyramid in an area that even the experts in the eighth rank couldn't find.