The effect of better-ear glimpsing on spatial release from masking.

The current experiment investigated whether better-ear glimpsing can explain the spatial release achieved by normal-hearing adults when situations are high in informational masking. Both modeling and behavioral methods were used. The speech reception thresholds of 38 young adults were measured for co-located, spatially separated and two better-ear glimpsed conditions. In the better-ear glimpsed conditions the binaural signals were processed so that in each time-frequency segment, the signal with the better SNR (left or right ear) was presented diotically. To investigate the effect of widening auditory filters on better-ear glimpsing, adjacent frequency bands were combined in one of the better-ear glimpsing conditions. Twenty-two participants were tested with maskers high in informational masking, while 16 participants were tested with maskers lower in informational masking. The mean speech reception thresholds achieved in the glimpsed conditions were significantly worse than in the spatially separated condition. This suggests that better-ear glimpsing can explain some but not all of the observed spatial release from masking. The difference between performance in the spatially separated and glimpsed conditions was largest when informational masking was high, suggesting better-ear glimpsing may release energetic rather than informational masking. Reducing the number of frequency bands sampled had a small effect on performance.