Results for Experiment 1.

A: Accuracy of story comprehension (left) and gist ratings (right). B: EEG prediction accuracy. C: Temporal response functions (TRFs). D: P1-N1 and P2-N1 amplitude difference for different speech-clarity conditions. Topographical distributions reflect the average across all speech-clarity conditions. The black asterisk close to the x-axis indicates a significant difference relative to the clear condition (FDR-thresholded). The absence of an asterisk indicates that there was no significant difference. Error bars reflect the standard error of the mean.

Results for Experiment 2.

A: Hit rate (left) and response times (right) for the visual n-back task. B: EEG prediction accuracy. C: Temporal response functions (TRFs). D: P1-N1 and P2-N1 amplitude difference for different speech-clarity conditions. Topographical distributions reflect the average across all speech-clarity conditions. The black asterisk close to the x-axis indicates a significant difference relative to the clear condition (FDR-thresholded). The absence of an asterisk indicates that there was no significant difference. Error bars reflect the standard error of the mean.

Depiction of stimulus samples.

A: Time courses for clear speech and speech to which background babble of speech-matched noise was added at 20 dB SNR (all sound mixtures were normalized to the same root-mean-square amplitude). The first 6 s of a story are shown. B: Spectrograms of the samples in Panel A. C: Power spectra for clear speech, babble, and speech-matched noise. In C, only background babble/noise is displayed, without added speech.

Results for Experiment 3.

A: Accuracy of story comprehension (left) and gist ratings (right). Higher vs. lower intensity refers to the two sound-level normalization types, one resulting a slightly lower intensity of the speech signal in the sound mixture than the other. B: EEG prediction accuracy. C: Temporal response functions (TRFs). D: P1-N1 and P2-N1 amplitude difference for clear speech and different speech-masking and sound normalization conditions. In panels A, B, and D, a colored asterisk close to the x-axis indicates a significant difference relative to the clear condition (FDR-thresholded). The specific color of the asterisk – blue vs red – indicates the normalization type (higher vs lower speech level, respectively). The absence of an asterisk indicates that there was no significant difference relative to clear speech. Error bars reflect the standard error of the mean.

Spectra for clear speech and different background noises.

Results for Experiment 4.

A: Accuracy of story comprehension (left) and gist ratings (right). B: EEG prediction accuracy. C: Temporal response functions (TRFs). D: P1-N1 and P2-N1 amplitude difference for clear speech and different speech-masking conditions. Topographical distributions reflect the average across all conditions. In panels A, B, and D, the black asterisk close to the x-axis indicates a significant difference relative to the clear condition (FDR-thresholded). The absence of an asterisk indicates that there was no significant difference relative to clear speech. Error bars reflect the standard error of the mean.

Results for Experiment 5.

A: Accuracy of story comprehension (left) and gist ratings (right). B: EEG prediction accuracy. C: Temporal response functions (TRFs). D: P1-N1 and P2-N1 amplitude difference for clear speech and different speech-masking and sound-delivery conditions. In panels A, B, and D, a colored asterisk close to the x-axis indicates a significant difference relative to the clear condition (FDR-thresholded). The specific color of the asterisk – blue vs red – indicates the sound-delivery type. The absence of an asterisk indicates that there was no significant difference relative to clear speech. Error bars reflect the standard error of the mean.