Effects of Critical Distance and Reverberation on Listening Effort in Adults

Abstract

Purpose: Mixed historical data on how listening effort is affected by reverberation and listener-to-speaker distance challenge existing models of listening effort. This study investigated the effects of reverberation and listener-to-speaker distance on behavioral and subjective measures of listening effort: (a) when listening at a fixed signal-to-noise ratio (SNR) and (b) at SNRs that were manipulated so that word recognition would be comparable across different reverberation times and listening distances. It was expected that increased reverberation would increase listening effort but only when listening outside critical distance. Method: Nineteen adults (21–40 years) with no hearing loss completed a dual-task paradigm. The primary task was word recognition and the secondary task was timed word categorization; response times indexed behavioral listening effort. Additionally, participants provided subjective ratings in each condition. Testing was completed at two reverberation levels (moderate and high, RT 30 = 469 and 1,223 ms, respectively) and at two listener-to-speaker distances (inside and outside critical distance for the test room, 1.25 and 4 m, respectively). Results: Increased reverberation and listening distances worsened word recognition performance and both behavioral and subjective listening effort. The effect of reverberation was exacerbated when listeners were outside critical distance. Subjective experience of listening effort persisted even when word recognition was comparable across conditions. Conclusions: Longer reverberation times or listening outside the room's critical distance negatively affected behavioral and subjective listening effort. This study extends understanding of listening effort in reverberant rooms by highlighting the effect of listener's position relative to the room's critical distance.