Panel a: behaviour of orbital frequencies and location of several resonant radii determined by the Ep and Kep models for a = 0.9. Panel b: behaviour of orbital frequencies and location of several resonant radii determined by the Ep and Kep models for a = 1.001. For Kerr black holes there is only one specific resonant radius for each displayed resonance, while even three resonant radii may appear for a single Ep model in the case of a super-spinning compact object or naked singularity.