  We study the quasinormal frequencies of three effective geometries of
nonrotating regular black holes derived from loop quantum gravity. Concretely,
we consider the Ashtekar-Olmedo-Singh and two Gambini-Olmedo-Pullin
prescriptions. We compute the quasinormal frequencies of axial and polar
perturbations adopting a WKB method. We show that they differ from those of
classical general relativity and, more importantly, that isospectrality is
broken. Nevertheless, these deviations are tiny, even for microscopic black
holes, and they decay following an inverse power law of the size of the mass of
the black holes. For the sake of completeness, we also analyze scalar and
vector perturbations, reaching similar conclusions.
