How Temporal Overlap in Task Processing and Acoustic Load Affect Listening Effort in Adults

Listening effort reflects the cognitive resources allocated to overcome obstacles in auditory processing. While acoustic degradation (e.g., noise, reverberation) is known to affect listening effort, little is known about how temporal overlap of task processing influences effortful listening in adults. This study examined behavioral and subjective listening effort in 26 adults using a sequential dual-task paradigm manipulating stimulus onset asynchrony (SOA; 0.05 s, 0.25 s, 1.5 s, single task), noise condition (silence, multi-talker babble at 0 dB SNR), and acoustic environment (anechoic, room effects of T₃₀ = 0.49 s). Task difficulty via decreasing stimulus onset asynchrony (SOA) significantly increased word recognition response times and subjective effort ratings, even when speech intelligibility remained high $\left(\sim 90\%\right)$. Noise effects emerged only at longer SOAs, but vanished at very short SOAs where capacity was exhausted, indicating that SOA is a stronger predictor of listening effort than noise exposure. Interestingly, mild reverberation reduced behavioral listening effort compared to anechoic conditions in silence.