Adaptation in vowels for real-time temporal perturbation

Real-time altered auditory feedback has demonstrated a key role for auditory feedback in both online feedback control and in updating feedforward control for future utterances. Much of this research has examined control in the spectral domain, and has found that speakers compensate for perturbations to vowel formants, intensity, and fricative center of gravity (Houde and Jordan, 1998; Jones and Munhall 2000; Patel et al. 2015, inter alia). However, there is just one study that examines the regulation of temporal control via auditory feedback (Mitsuya et al., 2014). In the current study we introduced a real-time perturbation of speech timing to examine control of relative timing between two distinct actions (VOT for /g, k/) and inherent timing of a single action (fricative duration for /s, z/). The introduced acoustic perturbation increased the duration of the target consonant and decreased the duration of the following vowel. Overall, speakers do not compensate for lengthened consonants. However, speakers do lengthen vowel productions in response to shortening, effectively decreasing the proportion of the syllable occupied by the consonant. Vowel lengthening effects persist after perturbation has ceased. These results indicate that speakers actively monitor duration and update upcoming plans accordingly.