The effects of intelligibility on conflict resolution and monitoring during speech recognition in noise.

Listeners have difficulty understanding speech in noisy environments, confusing similar sounding words. Cognitive control may be important for segregating the speech signal from background noise and/or selecting between phonological competitors in the mental lexicon. Although cognitive control abilities may be related to speech recognition in noise, the extent to which engaging cognitive control causally improves speech recognition in background noise is unclear. The present study presented pictures that matched (congruent trials) or were phonological neighbors (incongruent trials) of the spoken word to manipulate cognitive control during speech recognition in multitalker babble at + 6 and + 8 dB signal-to-noise ratios (SNRs). As conflict increases cognitive control levels, performance following incongruent trials indexes the effect of cognitive control on recognizing speech in noise. Following conflict, participants became faster and more accurate at repeating back speech at + 6 dB SNR and more accurate at + 8 dB SNR. When comparing across SNRs (including a + 4 dB SNR from a previous study), higher SNRs reduced the interference effect, predicting better recognition on incongruent trials; however, SNR did not significantly modulate postconflict improvements in word recognition. Results suggest engaging cognitive control improves speech recognition in noise across SNR levels where recognition is challenging but possible.