Listening Effort in Complex Audiovisual Scenes Under Varying Simulated Room Acoustic Conditions

Reverberation can degrade speech intelligibility and comprehension, increase cognitive load, and impair memory. Many studies examining reverberation effects use audio-only conditions and stationary background noise. Thus, it remains unclear to what extent findings generalise beyond laboratory setups. In the present study, we examine the influence of reverberation on memory and behavioural listening effort in a complex, audiovisual virtual reality (VR) environment. We implemented a virtual reality (VR) open-plan office with realistic room acoustics and time-varying background noise, including animated virtual agents. Three simulated room-acoustic conditions were compared: a free-field (T₃₀ = 0 s), an acoustically optimised office (T₃₀ = 0.5 s), and an untreated office (T₃₀ = 1.0 s). Under these conditions, N = 30 participants performed a dual-task. The primary Heard-Text Recall (HTR) task measured speech comprehension and memory. Participants listened to short stories narrated by two speakers and answered content-related questions. The vibrotactile secondary task measured listening effort. In single-tasking, memory for spoken content was significantly better in free-field than in both offices, with no significant difference between offices. In dual-tasking, vibrotactile response times indicated that listening effort increased in the presence of reverberation. Across single- and dual-task conditions, vibrotactile error rates decreased in the presence of reverberation, possibly due to elevated concentration in more difficult conditions. These findings suggest that room acoustics, compared to free-field environments, influence memory and listening effort in complex audiovisual VR and highlight the importance of incorporating reverberations when designing audiovisual environments for listening research.