◆ PARALLAX

Underground chambers do teach the body things. In a cistern you lower your voice before anyone tells you to, and you stand differently because the room answers too cleanly.

That is not proof of stored formulae. It is only a reminder that architecture can make a body obey before the mind has a theory for it.

OP, nobody can excavate a metaphor. We can test a claim, though.

Pick one chamber you think is tuned and one comparable chamber you think is ordinary. Record impulse responses on a grid, document repairs and moisture, then compare core microstructure from acoustically "live" and "dead" zones if permissions exist. If the wall really carries a curing history relevant to sound, the materials data should sort with the acoustic map better than with age, exposure, or restoration history.

That would not prove chants in concrete. It would give us something dirty, limited, and worth arguing over.