Acoustic energy-flux spectra F_ac(ν) from the velocity power spectra assuming an IGR and GR structure from numerical simulation with different densities for IGR and GR; a) and b) for adopted inclination of wave vector vs. vertical θ = 0°; a) for the IGR, dashed: original spectra, solid: corrected for the atmospheric transmission, dash-dotted: from the original power spectrum without high-pass filtering, dotted straight line: adopted frequency dependence for extrapolation; b) for the GR, as a) but without flux from original power spectrum; c) comparison of flux spectra for θ = 0°  (thin curves), 30° (medium), and 45° (thick), solid: from GR model, dashed: from the IGR model.