I'd say your proof is no proof, particularly since the Egyptians (unlike the Mayans) didn't build structures that made use of channeling sound or funneling sound. In order to measure by sound, they would have to have an accurate measurement of time and it would have to be able to measure time in far smaller units than the second.

You could get the same sorts of results simply by laying the thing out with no other purpose than "it's pleasing to the eye when viewed from the palace at the city of Cairo."