Auditory streaming and rhythmic masking release in Cope's gray treefrog

Auditory streaming involves perceptually assigning overlapping sound sequences to their respective sources. Although critical for acoustic communication, few studies have investigated the role of auditory streaming in nonhuman animals. This study used the rhythmic masking release paradigm to investigate auditory streaming in Cope's gray treefrog (Hyla chrysoscelis). In this paradigm, the temporal rhythm of a Target sequence is masked in the presence of a Distractor sequence. A release from masking can be induced by adding a Captor sequence that perceptually "captures" the Distractor into an auditory stream segregated from the Target. Here, the Target was a sequence of repeated pulses mimicking the rhythm of the species' advertisement call. Gravid females exhibited robust phonotaxis to the Target alone, but responses declined significantly when Target pulses were interleaved with those of a Distractor at the same frequency, indicating the Target's attractive temporal rhythm was masked. However, addition of a remote-frequency Captor resulted in a significant increase in responses to the Target, suggesting the Target could be segregated from a separate stream consisting of integrated Distractor and Captor sequences. This result sheds light on how auditory streaming may facilitate acoustic communication in frogs and other animals.