Figure 1.
A. A schematic diagram of the setup used for AF perturbation during speech. B. A schematic showing an example of the ordering of the noPert (baseline), Down, and Up trials in Experiment 1. Note the rule that two perturbation trials were separated by at least one intervening noPert trial. C. Example spectrograms of the monophthong [ε] in the word “head”: the original (noPert) spectrogram (left), 20% Up shift (center), and 20% Down shift (right). The dashed white curves show the original tracked F1 trajectories; the dashed cyan curves display the perturbed F1 trajectories.
Table 1.
Summary of the vowel durations and levels produced under the three perturbation conditions (noPert, Down and Up) by the PFS (control) and PWS participants.
Figure 2.
Compensatory adjustments of produced F1 trajectories under the Down and Up perturbations in PWS and PFS participants.
A. Individual participants’ F1 trajectory changes from the noPert baseline, plotted as a function of time since vowel onset. Each blue (red) curve shows the data from the Down (Up) condition of one subject. The left and right parts of this plot show data of the fluent control (PFS) and PWS groups, respectively. This panel is based on the full data set (see text for details). B. Averages drawn from the same data as shown in Panel A. Solid curves: average F1 trajectory difference between the perturbed and noPert conditions, across all 18 PFS (left) and 21 PWS (right); dashed curves: mean±1 SEM. The three horizontal bars on the bottom of this panel indicate significant differences under three comparisons as functions of time. From top to bottom: Down vs. noPert, Up vs. noPert, and Down vs. Up. In each bar, the lighter color (lighter blue, lighter red, or lighter gray) indicates significance at an uncorrected threshold of p<0.05. The darker color (e.g., darker blue, darker red, or black) indicates significance at a corrected level of FDR = 0.05. C. Same format as B, but with average F1 change trajectories computed based on the limited data set (see text for details).
Figure 3.
Different cross-trial adaptation responses in the PWS and PFS groups.
The data used in generating this figure included Down and Up trials that were separated from the preceding perturbation trial (of the opposite type) in the same block by two or fewer trials, i.e., the small-spacing trials (see text for details). The formant frequency values in the first 50 ms of the vowel were averaged to generate the displayed results. Note the existence of the cross-trial adaptation effects, as shown by the large changes from the noPert condition, in the PFS group, and the lack thereof in the PWS group.
Figure 4.
Average composite response curves from the PWS (purple) and PFS (black) groups.
A and B: The composite compensation curves were computed by subtracting the F1 change profile under the Up perturbation from the F1 change profile under the Down perturbation. The horizontal bars below indicate significance of the difference between the two groups as a function of time (two-sample t-test, two-tailed). Gray: significance on the uncorrected level of p<0.05. Panels A and B illustrate the results from the full and limited data sets, respectively. Notice that the scales of the ordinates of Panels A and B are different. C and D: the composite response curves shown on a coarser time scale than in A and B. Eleven equally spaced time points were placed between 0 and 300 ms following vowel onset (30-ms separations). The error bars in these two panels show ±1 SEM. The asterisks at the top of the figure indicate time bins in which the difference between the PWS and PFS groups were statistically significant according to post hoc t-tests that followed the finding of significant GROUP×TPT interaction in the mixed ANOVA (see text for details). Results in C and D are based on the full and limited data sets, respectively.
Table 2.
Proportions of compensating, unresponsive and following responses under the Down and Up perturbations in the two groups of subjects.
Figure 5.
Variability of F1 production in PWS and PFS under the three perturbation conditions.
The black and purple curves show mean within-subject, across-trial standard deviations (SDs) of produced F1 in PFS and PWS, respectively. The error bars show ±1 SEM. Notice the lack of significant differences in the SD of produced F1 between groups and between perturbation conditions. This figure shows the results from the limited data set, but similar conclusions can be drawn based on the full data set.
Figure 6.
Calculation of the latencies of the compensatory response to the Down and Up perturbations in individual PWS and PFS participants.
A. An example of the Cohen’s d scores of the differences between the F1 trajectories produced under the Down and Up conditions by an individual subject (blue). A two-segment spline (dashed magenta) was fitted to the Cohen’s d curve. The inflection (break) point of the spline, determined as the response latency of this subject, is shown by the square. The latency of the compensatory response, determined as the zero-crossing time of the fitted spline, is shown by the blue square (see text for details). B. Comparison of the group means of the response latencies between the PFS and PWS. These results were obtained from the limited data set (see text for details).
Figure 7.
Auditory acuity to differences in F1 of the vowel [ε] and its relation to the magnitude of the compensation to perturbation.
A. Comparison of the vowel F1 JNDs between the PFS and PWS groups. A fraction of perturbation equal to 1 corresponds to the same magnitude of perturbation as used in the production experiment. B. Correlation between the F1 JNDs (abscissa) and the magnitude of the compensation to the AF perturbation (ordinate). Compensation magnitudes from the limited data set analysis are used in this plot. The fraction difference between the F1 produced under the Down and Up conditions, at 300 ms following vowel onset, is used as a measure of compensation magnitude. The black and purple circles show the data from the PFS and PWS participants, respectively.