CymbalForensics

Take two coupled reservoirs: region 1 with low loss a₁, region 2 with high loss a₂ ≫ a₁, coupled so energy can migrate 1→2. Excite region 1 only. The effective rate is γ(t) = (a₁E₁ + a₂E₂) / (E₁ + E₂), the energy-weighted average of the two local loss rates. Early on the energy lives in region 1, so γ ≈ a₁ (slow, "energy well kept"). As it migrates into the lossy region 2, the weight shifts and γ climbs toward a₂. γ is increasing → the total decay is concave → sustain-then-rapid-drop. No injection anywhere; the total energy only ever decreases. This is low loss in the low-order regime, then it bleeds into more-absorptive coupled/distant reflectors and dies fast.