Hierarchical modulation, used in DVB-{T, H} (digital video broadcasting - terrestrial and handheld), allows two separate bit streams to be modulated on one single stream according to their relative priority (high priority and low priority stream). We investigate the robustness of coupled OFDM (orthogonal frequency division multiplex) and hierarchical modulation systems under impulse noise as it appears in DVB (digital video broadcasting) technologies. Analytically and confirmed by simulation, we estimate the penalty induced by the presence of impulse noise.