Territorial males of the pan-Amazonian Dart-poison frog, Epipedobates femoralis, are known to present stereotypic phonotactic responses to the playback of conspecific and synthetic calls. Fixed site attachment and a long calling period within an environment of little temperature change render this terrestrial and diurnal pan-Amazonian frog a rewarding species for field bioacoustics. In experiments at the field station Aratai, French Guiana, we tested whether the prominent frequency modulation of the advertisement-call notes is critical for eliciting phonotactic responses. Substitution of the natural upward sweep by either a pure tone within the species frequency range or a reverse sweep did not alter the males' phonotactic behavior. Playbacks with artificial advertisement calls embedded in high levels of either low-pass or high-pass masking noise designed to saturate nerve fibers from either the amphibian papilla or basilar papilla showed that male phonotactic behavior in this species is subserved by activation of the basilar papilla of the inner ear.