Charged particle $p_{\rm T}$ distribution measured in Pb-Pb collisions in different centrality intervals. The spectra are scaled for better visibility. The dashed lines show the pp reference spectra scaled by the nuclear overlap function determined for each centrality interval and by the Pb-Pb spectra scaling factors. The systematic and statistical uncertainties for Pb-Pb are added quadratically. The uncertainties on the pp reference are not shown.