Speaker
Description
The perceived location of a sound is influenced by preceding (precursor) sounds. In the horizontal plane, lateral precursors shift the perceived location of a subsequent probe sound toward the midline, whereas central precursors push perceived locations further toward the sides. These effects are typically stronger for headphone presentation than for loudspeaker playback in anechoic environments. We hypothesized that accurate, listener-specific spectral cues provided by loudspeaker presentation enhance spatial precision and thus reduce precursor effects. To that end, we manipulated spectral cues by progressively smearing head-related transfer functions (HRTFs) using cepstral smoothing, thereby reducing spectral detail while preserving binaural localization cues. Participants performed a headphone-based localization task in a virtual audiovisual environment using a VR headset in an anechoic room. Visual markers at 0°, 45°, and 90° allowed participants to realign their position after each trial. Probe sounds were presented from −90° to 90° in 10° increments. Precursors were delivered at −70°, 0°, or 70°, or omitted in a control condition without precursors. Probe and precursor sounds were pink noises with durations of 600 and 300 ms, respectively, separated by 10 ms of silence. Listeners were instructed to focus on the probe. Preliminary results show small but reliable precursor effects within listeners, with notable variability across individuals. Crucially, reducing spectral cues did not significantly change the magnitude of the precursor effect. Consistent with this finding, spectral cues also did not affect localization accuracy in the absence of precursors. Overall, the results do not support the hypothesis that spectral cues mitigate spatial precision and precursor-induced spatial biases in the frontal horizontal plane.