Fig 1.
Block design of fNIRS experiment.
Stimuli and rest times in an example test period are shown. Eighteen-second duration stimuli were presented twice at each level in counterbalanced order. Rest periods were 25, 30 or 35 seconds (chosen at random). One recording session consisted of 5 test periods with breaks of 2–3 minutes in between.
Fig 2.
Percentage change in heart rate relative to baseline.
(A) Percentage change in heart rate relative to baseline, averaged across participants (n = 27). Shaded areas show standard error of mean (SEM). (B) Mean heart rate change from t = 0 to 8 s relative to stimulus onset, averaged across participants. Boxes represent median, interquartile range and largest/ smallest non-outliers. Crosses represent outliers or values greater than 1.5 times the interquartile range. *** P<0.001.
Fig 3.
Inter-beat intervals across time for a representative participant.
Vertical lines show the times sound stimuli at different levels were applied.
Fig 4.
Percentage change in averaged inter-beat intervals relative to baseline.
Values averaged across participants (n = 27) are shown. Error bars show standard error of mean (SEM).
Table 1.
Mean (95% confidence interval) percentage change in inter-beat intervals from baseline, across participants.
Table 2.
Comparison between mean percentage change from baseline (95% confidence interval of difference) at different stimulus levels, across inter-beat intervals three to five.