Do nonnative listeners benefit as much as native listeners from spatial cues that release speech from masking?

Since most everyday communication takes place in less than optimal acoustic settings, it is important to understand how such environments affect nonnative listeners. In this study we compare the speech reception abilities of native and nonnative English speakers when they are asked to repeat semantically anomalous sentences masked by steady-state noise or two other talkers in two conditions: when the target and masker appear to be colocated; and when the target and masker appear to emanate from different loci. We found that the later the age of language acquisition, the higher the threshold for speech reception under all conditions, suggesting that the ability to extract speech information from masking sounds in complex acoustic situations depends on language competency. Interestingly, however, native and nonnative listeners benefited equally from perceived spatial separation (an acoustic cue that releases speech from masking) independent of whether the speech target was masked by speech or noise, suggesting that the acoustic factors that release speech from masking are not affected by linguistic competence. In addition speech reception thresholds were correlated with vocabulary scores in all individuals, both native and nonnative. The implications of these findings for nonnative listeners in acoustically complex environments are discussed.