The effect of nearby maskers on speech intelligibility in reverberant, multi-talker environments

The extent to which informational masking (IM) is involved in real-world listening is not well understood. In the literature, IM effects of more than 8 dB are reported, but these experiments typically used simplified spatial configurations and speech materials with exaggerated confusions. Westermann and Buchholz [(2015b). J. Acoust. Soc. Am. 138, 584-593] considered a simulated cafeteria and found only substantial IM effects when the target and maskers were colocated and the same talker. The present study further investigates the relevance of IM in real-world environments, specifically distractions by nearby maskers and the effect of hearing impairment. Speech reception thresholds (SRTs) were measured with normal hearing (NH) and sensorineural hearing impaired (HI) listeners in a simulated cafeteria environment. Three different masker configurations were considered: (1) seven dialogues distributed in the cafeteria, (2) two monologues presented close to the listener with varying angular separation, and (3) a combination of (1) and (2). The contribution of IM was measured as the difference in SRTs between speech maskers and unintelligible vocoded maskers. No significant IM was found with the seven dialogues alone. Including nearby maskers resulted in substantial IM for both NH and HI listeners, suggesting that such maskers might result in IM in real-world environments.