CDN-192: The Selector Is Missing

CDN-192 attacks the remaining D9 floor derivation by deriving and testing the acoustic response operator behind the imported CDN-179 floors. The exact acoustic branch and driven R = 2f + theta_t transfer function localize the floors to finite acoustic wave numbers inside the measured response band, but neither a universal sigma*k = 1 rule nor a simple retarded response-force peak reproduces all three floors. The high-xi branch is nearly recovered, while the low and mid branches are overpredicted. D9 therefore remains unpaid: the missing object is the branch-dependent spectral selection kernel.