Article Figures & Data
Figures
- Figure 1.
Experimental procedure. A, Front vowels used in the study (simplified representation) (Ladefoged, 2001). B, F1 shift for different experimental groups. B1, Experiment 1. F1 in “head” was increased toward “had” and F1 in “had” was decreased toward “head.” B2, Experiment 2. F1 in “head” was decreased and F1 in “had” was increased. B3, Experiment 3. F1 was increased for “bed,” decreased for “head,” and unaltered for “ted.” B4, Experiment 4. F1 was increased in both “head” and “bed” and unaltered for “ted.” Arrows on the F1 and F2 axes show the direction of F1/F2 increase. C, Experimental sequence. Each session included the same number of productions of each word in random order. After an initial block with unaltered feedback, the perturbation of the auditory feedback was introduced in five steps, maintained for six blocks, and returned to normal in the final block. Blanks between blocks indicate short breaks. The total number of repetitions of each word was 290 in experiments 1 and 2 (C1) and 210 in experiments 3 and 4 (C2).
- Figure 2.
Experimental set-up. The subject read words aloud and heard his altered voice through open earphones. The sound pattern of “head” (spectrogram shown in A, formant tracking in green) was altered to sound like “hid” (F1 shifted downward, spectrogram shown in B, formant tracking in red). The selective shift of F1 was accomplished by using an acoustical effects processor in combination with filters and mixing devices.
- Figure 3.
A, B, Average values of F1 and F2 relative to frequencies in prelearning trials for experiments 1 (A, first row) and 2 (B, second row). Left, Curves give the progression of frequency change over the course of learning. Right, Bar graphs show means and the SEs for learning and aftereffects. Asterisks indicate reliable differences (p < 0.05). A, In experiment 1, F1 auditory feedback was shifted down for “had” and up for “head.” In response to the perturbation, subjects increased F1 values for “had” and decreased F1 for “head.” B, In experiment 2, a change in F1 opposite to that in experiment 1 resulted in opposing compensations. In both experiments, F2 tended to change in a direction opposite to F1 for “head” whereas no clear change of F2 was observed for “had.”
- Figure 4.
A, B, Average values of F1 and F2 relative to prelearning frequencies in experiments 3 (A, left) and 4 (B, right). For each experiment, the curves on the left represent the progression of frequency changes over the courses of learning for F1 (bottom) and F2 (top). Right, Bar graphs show the means and the SEs for learning and aftereffects. Asterisks indicate reliable effects (p < 0.05). A, In experiment 3, F1 auditory feedback was increased for “bed,” decreased for “head,” and unaltered for “ted.” In response to these perturbations, the subjects progressively decreased F1 in “bed” and increased F1 in “head.” B, In experiment 4, F1 was increased in both “head” and “bed” and unaltered for “ted.” Subjects compensated for the perturbation by progressively decreasing F1 in both “bed” and “head.” In both experiments, F2 values tended to change in a direction opposite to F1 for the shifted words. No systematic modification of F1 or F2 appeared for the unshifted frequencies in “ted.”
