Reverberation detection threshold estimates in normal-hearing listeners

Abstract

The study of human sensitivity to a single acoustic reflection (echo) has a long and rich history. The influence of time delay, level, direction, and source material are well documented. Unfortunately, real world listening seldom involves only a single reflection. Multiple reflections and reverberation are instead the norm. It is therefore surprising that the detection threshold for acoustical room effects (early reflections plus reverberation) has not been extensively studied, if at all. This study represents an initial step to fill this gap in knowledge. Using virtual auditory space techniques to simulate room acoustic sounds fields over headphones, the detection threshold for reflected/reverberant sound energy was measured for three sound field conditions: a small office-sized room (broadband T60 = 0.5 s), a concert hall (broadband T60 = 1.5 s), and a reference condition with a single echo at 40 degrees to the right of midline. The source signal was a 220 Hz complex tone, 250 ms in duration. Thresholds for the single-echo reference condition and the small room condition were found to be comparable, whereas the concert hall produced thresholds that were at least 20 dB lower. Temporal integration and binaural effects are considered as potential explanations for these results.