Variation of total absorbed and emitted fluxes (left panel) and the ratio of the total absorbed-to-emitted flux (right panel) using the O9 simulated sky and the assumptions listed in Sect. 2. The results are for all sources within voxels defined by channel width of 1 MHz, placed at various redshifts. Note though that the ratio of the total absorbed-to-emitted flux remains unchanged for channel widths ranging between 0.1 and 10 MHz.