Figure 3: FFT Spectral Analysis of K Residuals (Standing Wave Frequency) Frequency (cycles per window doubling) Spectral Power (arbitrary units) 0.0 0.25 0.5 0.75 1.0 1.25 1.5 0.0 0.2 0.4 0.6 0.8 1.0 f₀ = 0.6667 cycles/window (Period = 1.5 doublings) f = 1.0 (performance wave) 3:2 frequency ratio (perfect fifth in musical terms) Dominant frequency (f₀ = 0.6667, p < 0.0001) Secondary harmonic (performance oscillation, f = 1.0) Noise floor Statistical Significance f₀ = 0.6667 ± 0.02 cycles/window p-value < 0.0001 R² = 0.994 (FFT model fit)