Spectra obtained with a 40-day sequence of model sem-lin at r₀ = 0.65 R_⊙ (top panel) and r₀ = 0.44 R_⊙ (bottom panel). Although the horizontal N_θ = 512 resolution of this model allows reaching ℓ_max = 340 (see Eq. (20)), we have cut the horizontal axis to ℓ = 170 to focus on the difference between both spectra. At low frequency, the waves visible at r₀ = 0.65 R_⊙ have been totally damped at r₀ = 0.44 R_⊙.