Effects of room acoustics on subjective workload assessment while performing dual tasks

Abstract

This investigation examines the subjective workload assessments of individuals using the NASA Task Load Index (TLX), as they performed speech comprehension tests under assorted room acoustic conditions. This study was motivated due to the increasing diversity in US classrooms. Both native and non-native English listeners participated, using speech comprehension test materials produced by native English speakers in the first phase and by native Mandarin Chinese speakers in the second phase. The speech materials were disseminated in an immersive listening environment to each listener under 15 acoustic conditions, from combinations of background noise level (three levels from RC-30, 40, and 50) and reverberation time (five levels from 0.4 to 1.2 seconds). During each condition, participants completed assorted speech comprehension tasks while also tracing a moving dot for an adaptive rotor pursuit task. At the end of each acoustic condition, listeners were asked to assess the perceived workload by completing the six-item NASA TLX survey, e.g., mental demand, perceived performance, effort, and frustration. Results indicate that (1) listeners’ workload assessments degraded as the acoustic conditions became more adverse, and (2) the decrement in subjective assessment was greater for non-native listeners.