The auditory system takes advantage of early reflections (ERs) in a room by integrating them with the direct sound (DS) and thereby increasing the effective speech level. In the present paper the benefit from realistic ERs on speech intelligibility in diffuse speech-shaped noise was investigated for normal-hearing and hearing-impaired listeners. Monaural and binaural speech intelligibility tests were performed in a virtual auditory environment where the spectral characteristics of ERs from a simulated room could be preserved. The useful ER energy was derived from the speech intelligibility results and the efficiency of the ERs was determined as the ratio of the useful ER energy to the total ER energy. Even though ER energy contributed to speech intelligibility, DS energy was always more efficient, leading to better speech intelligibility for both groups of listeners. The efficiency loss for the ERs was mainly ascribed to their altered spectrum compared to the DS and to the filtering by the torso, head, and pinna. No binaural processing other than a binaural summation effect could be observed.

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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.

Numerous studies have described improvements in speech understanding when interaural time differences (ITDs) and interaural level differences (ILDs) are present. The present study aimed to investigate whether either cue in isolation can elicit spatial release from masking (SRM) in a speech-on-speech masking paradigm with maskers positioned symmetrically around the listener. Twelve adults were tested using three presentations of the Listening in Spatialized Noise-Sentences Test, with each presentation modified to contain different interaural cues in the stimuli. Results suggest that ILDs provide a similar amount of SRM as ITDs and ILDs combined. ITDs alone provide significantly less benefit.