Effects of room acoustics on speech intelligibility
In daily life, speech communication often takes place in rooms with interfering sounds, where speech intelligibility (SI) is affected by (i) masking and (ii) reverberation. For both spectral and temporal changes to the signal are relevant. A critical spatial configuration to assess SI is a frontal target speaker and two interfering sources symmetrically placed to either side (±60°). Here a spatial release from masking (SRM) is observed in comparison to co-located frontal target and interferers, showing that the auditory system can make use of temporally fluctuating interaural differences. Room reverberation affects the temporal representation of the target and maskers and, moreover, the interaural differences depending on the spatial configuration and room acoustical properties. Here the effect of room acoustical properties (room size,T60), temporal structure of the interferers (stationary and fluctuating), and direct-to-reverberation ratio (DRR) on speech reception thresholds (SRT) and SRM were systematically assessed in a simulated room using headphone-based virtual acoustics. Further, the contribution of short-time better-ear glimpses to SRM for symmetrically placed maskers and different room acoustical properties was assessed by applying an ideal monaural better-ear mask (IMBM). SRTs from stimuli with binaural information are compared to those from diotically presented stimuli based on the IMBM.