Frequency power spectrum of the vertical velocity component υ extracted in the middle of the stable layer at (x, y, z) = (−0.2, 2.5, −0.2) over the time series t ∈ (10τ_conv, 32τ_conv) in the problem of turbulent convection and wave excitation. The left and right panels show results obtained on the 128³ and the 256³ grid, respectively. Each row of panels shows the results of simulations run using 6 reconstruction schemes with the same Riemann solver. The reference solution (indicated with REF) is the black curve. The convective turnover frequency (ω_conv = 2π/τ_conv), the Brunt-Väisälä frequency at (x, y, z) = (−0.2, 2.5, −0.2) (N_BV), and the frequency of the fundamental oscillation mode of the cavity (ω₀ = 1.1) are represented by the black dashed-dotted, dashed, and dotted lines, respectively.