Serial recall in spatial acoustic environments: irrelevant sound effect and spatial source alternations

This study investigated serial recall performance in a complex acoustic scene that included spatialised background sounds and location changes within the target sequence to reflect real-life challenges. The focus is on two effects: the irrelevant sound effect (ISE) and the spatial-source alternation effect (SSAE). Both represent impairment in short-term memory performance of to-be-remembered items: the ISE due to irrelevant background sounds, and the SSAE due to location changes within the target sequence. Although distinct, these effects typically occur together in real-world settings, e.g., listening to multiple speakers in noise, but have not been investigated together yet. Building on the theoretical frameworks of these two effects, this study combines principles from both the irrelevant sound effect (ISE) and the spatial-source alternation effect (SSAE) as a step towards enhancing acoustic complexity in established cognitive tasks. Experiment 1 examined auditory-verbal serial recall using spatially alternating target digits presented at a typical rate (1 item/1 s), with either meaningful or meaningless background speech. Results showed an ISE, with meaningful speech causing greater disruption, but no SSAE - possibly due to either the presentation rate or the spatialised audio scene. To further clarify this, Experiment 2 was conducted with a faster presentation rate (1 item/350 ms) consistent with a previous study, and more spatial target locations (monotic, [Formula: see text]). An SSAE was revealed for all locations. These findings suggest that the SSAE may mainly be modulated by the presentation rate-given the spatial separation is audible and only emergent at rapid location changes-questioning its applicability to naturalistic listening scenarios. As an attempt to bridge the gap between controlled laboratory settings and more complex listening tasks, these findings help explain how cognitive systems manage competing demands in real-world auditory environments, such as separating speech streams in noise.