Dissecting the Contribution of Sensory Cues to Directional Responses by Female Crickets in a two-Loudspeaker Paradigm

Sound localization in insects is typically investigated using single loudspeaker paradigms to examine the impact of sensory cues. Here, the contribution of specific cues to turning responses in a two-loudspeaker paradigm equivalent to a choice situation was examined. For that, several sensory cues were systematically varied to determine their respective contribution to the strength of the turning response in female crickets. In three experimental sets (1) the temporal arrangement of chirp patterns broadcast from two speakers, (2) the relative timing of chirps and (3) the impact of phase differences of the carrier frequency were varied at different intensity levels between both speakers. While the arrangement of chirp patterns had little influence on the strength of turning responses, time delays up to 20 ms and phase differences of 90° and 270° clearly affected directional turning at otherwise equal intensities. In all three sets of experiments turning responses were sensitive to intensity differences and saturated at +/− 6 dB. Turning responses due to timing of pulses or phase differences were compensated by intensity differences of 2–3 dB. Building on a large body of literature on peripheral and central processing it was possible to assign the observed effects to specific processing stages in the auditory pathway of crickets.