GCFT CDN-175: Sigma-Universality of the Acoustic Floor — Floor Position c_s(Δ) Confirmed Universal, Convergence Rate Governed by Δ·σ², σ∈{8,16,32}

CDN-175 (Coherence Domain Nucleation audit note 175) in the General Coherence Field Theory (GCFT) series, Project Aporion. Pre-registered in CDN-174. Tests σ-universality of the acoustic floor v*(Δ) → c_s(Δ) = √(Δ/(Δ+4)) established in CDN-173/174 at σ=16. Runs 35 simulation pairs at σ∈{8,32} using the T=20σ/c_s protocol, Δ∈{0.040,0.060,0.080,0.100}. Finding: the floor POSITION c_s(Δ) is confirmed σ-universal. The residual excess ε = v*/c_s − 1 at finite T is governed by the dimensionless ratio ξ = Δ/Δ_c(σ) = Δ·σ²: σ=8 (ξ~3–6) gives ε~9–18%; σ=32 (ξ~60–100) gives ε~−0.5%, essentially at the floor. All three σ values collapse onto a single ε(ξ) curve. The two-parameter convergence law ε(ξ, T/τ_local) is pre-registered for CDN-176. Lock code: CDN175_SIGMA_DEPENDENT_INVESTIGATE_FLOOR_UNIVERSAL_CONV_RATE_DELTA_SIGMA2 Includes: simulation script (gcft_cdn175_sigma_universality.py), checkpoint JSON, results JSON, 3-panel figure, TeX note, Art Edition PDF.