Figure 5.

Alpha power relates to subjective difficulty measures. A, Alpha power modulation (reflecting mean linear coefficients of alpha power changes with each level of acoustic detail and predictiveness across four significant clusters) as a function of participants' self-reported subjective listening effort in background noise (significant Spearman correlation, p = 0.002). Data for younger and older participants are shown in black and magenta, respectively. B, Left, Bars represent mean confidence ratings for trials with low, medium, and high alpha power. Between-condition effects were eliminated by binning trials according to alpha power separately for each factor combination of acoustic detail and predictiveness. Red dashed line indicates the mean linear fit to confidence ratings. Confidence ratings decreased with higher alpha power (p = 0.001). Right, Bars represent the average linear coefficients (quantifying changes in confidence ratings with each level of alpha power) for younger (black) and older (magenta) participants. Error bars indicate ± 1 SEM. **p < 0.01. n.s., Not significant.