This study explored speech intelligibility and free recall of word lists heard under different signal-to-noise (S/N) ratios. Pre-experimental measures of working memory capacity (WMC) were taken to explore individual susceptibility to the disruptive effects of noise. The thirty-five participants first completed a WMC-operation span task in quiet and later listened to spoken word lists containing 11 one-syllable phonetically balanced words presented at four different S/N ratios (+12, +9, +6, and +3). Participants repeated (shadowed) each word aloud immediately after its presentation and performed a free recall task of the words after the end of the list. The speech intelligibility function decreased linearly with increasing S/N levels for both the high-WMC and low-WMC groups. Recall and memory of the words decreased with increasing S/N levels only for the low-WMC group. Recall and memory for the high-WMC individuals was not affected by increased S/N levels. Our results suggest that impoverished acoustical conditions impair speech intelligibility and memory, but also that a high WMC may counteract some of the negative effects of speech noise.
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