Integration of conflicting acoustic cues in sound localization in Cope's gray treefrog

Sound localization is crucial for acoustically communicating organisms. However, many species must localize sounds in challenging conditions with high noise and signal degradation, which in some cases generate conflicting directional cues. Neural integration of repeated signal elements could improve the accuracy of sound localization, but little is known about how directional cues are integrated in natural animal acoustic communication. We studied how female Cope's gray treefrogs (Hyla chrysoscelis) integrate conflicting directional information in male acoustic advertisement calls. We performed two-speaker phonotaxis experiments in which two speakers broadcast overlapping synthetic advertisement calls in which we systematically manipulated the timing relationships of pulses within the calls such that some pulses were leading in time on one speaker and the remaining pulses were leading on the other speaker. We tested alternative hypotheses of the mechanisms of integration by examining the effects of the percentage of leading pulses and their temporal order (at the beginning or end of the call) on female response to a speaker and the latency to approach. Our results were consistent with integration across the entire call, and females moved towards whichever side broadcast the greater percentage of leading pulses, with no evidence for temporal order effects. We also found that females took longer to approach for stimuli with highly conflicting directional information. These findings give insights into the mechanisms of sound localization and information integration in challenging acoustic conditions.