Authors: Emil Zawistowski¹, Mikołaj Sęklewski², Jakub Zając²
¹Aalborg University; ²University of Warsaw
Background: Subitizing—the rapid, accurate enumeration of small quantities—is well-documented in vision but remains poorly understood in audition, especially for simultaneous stimuli. While spatial separation is thought to facilitate auditory object individuation, it is unclear whether this benefit stems from alignment with specific spatial channels or the mere distribution of sounds across locations. This study compared two spatial configurations to investigate these mechanisms.
Method: Twenty-four normal-hearing adults performed an online enumeration task (1–6 simultaneous naturalistic sounds) using HRTF-based spatial rendering. In Experiment 1, sounds were distributed across three locations (-90°, 0°, 90°), allowing multiple sounds per location. In Experiment 2, sounds were spread across six distinct locations (0°, ±60°, ±120°, 180°), with a maximum of one sound per location. Accuracy and response times (RT) were compared, and individual subitizing ranges were calculated.
Results: A trade-off between speed and accuracy was observed. Participants were significantly faster in the three-location configuration (Experiment 1; p = .012, d = 0.58). Conversely, accuracy showed a trend toward higher performance in the six-location configuration (Experiment 2; p = .063, d = -0.42), though this did not reach statistical significance.
Conclusion: Spatial distribution influences auditory enumeration, but the results present a complex relationship where greater separation may improve accuracy at the expense of response speed. These mixed findings highlight the need for further research using individualized HRTFs or physical loudspeaker arrays to create more realistic acoustic scenes and clarify the role of spatial hearing in auditory subitizing.
