Comparison of the averaged periodograms of photometric (red) and spectroscopic (black) observations. Left: Solar VIRGO (red SPM channel) and GOLF observations. Middle: CHEOPS and ESPRESSO observations of HD 67458. Right: same for HD 88595. The periodograms have been arbitrarily normalized to compare their slope in the frequency regime that is dominated by stellar granulation. When relevant, the different cut-off frequencies v_cut, v_max, f_H, and f_g represented by the green, blue, cyan and magenta vertical lines, respectively.