Presentation
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Sensitivity to auditory feedback and individual variability
Poster D57 in Poster Session D, Wednesday, October 25, 4:45 - 6:30 pm CEST, Espace Vieux-Port
Muge Ozker Sertel1, Peter Hagoort1,2; 1Max Planck Institute for Psycholinguistics, 2Donders Institute for Brain, Cognition and Behavior
Monitoring auditory feedback is important for fluent speech production as it enables detection and correction of vocalization errors. Influence of auditory feedback is best illustrated by manipulating it during speech production. A common temporal manipulation technique is delaying auditory feedback (DAF), which disrupts speech fluency, and a common spectral manipulation technique is perturbing the pitch of auditory feedback, which elicits vocal changes in the opposite direction of the perturbation. Interestingly, not everybody is equally sensitive to auditory feedback manipulations, however the reason for this individual variability is unknown. In this study, we aimed to understand whether there is a correlation between sensitivity to temporal versus spectral manipulations of auditory feedback. And whether less sensitive individuals rely less on auditory feedback when an alternative source of sensory feedback (e.g. visual) is available. To address these questions, we collected data from 40 native Dutch speakers (20 females, mean age: 24.5) during both a DAF and a pitch perturbation task. In the DAF task, participants repeated auditorily presented sentences. Auditory feedback was presented either simultaneously or with 200ms delay. In half of the trials visual feedback was presented additionally via a webcam. Voice recordings of the participants were analyzed using linear mixed effect (LME) models to test the effects of four factors (delay, visual feedback, gender and trial structure) on three speech measures (articulation duration, voice intensity and voice pitch). In the pitch perturbation task, participants phonated the vowel /a/ for 4 seconds and pitch of the auditory feedback was shifted by 100 or 200 cents for 300ms at a random latency. LME models were used to test the effects of three factors (shift magnitude, shift direction and gender) on three speech measures (compensatory response magnitude, response latency and percentage of opposing responses). We found that DAF significantly prolonged articulation duration and increased both voice pitch and intensity, but participants’ speech rate increased as the experiment progressed. In contrary to our expectations, visual feedback did not ameliorate but reinforced the disruptive effects of DAF. For the pitch perturbation task, we only found that larger pitch shift elicited less compensatory responses. We used articulation duration and compensatory response magnitude to measure sensitivity in the DAF and pitch perturbation tasks, respectively. There was a large individual variability in sensitivity to auditory feedback manipulations for both tasks, however there was no correlation between the sensitivity profiles between tasks. Our results demonstrated that an individual can be sensitive to temporal but not necessarily to spectral manipulations of the auditory feedback, or vice versa, suggesting that these features are processed differently. We also showed that, possibly because visual feedback is not naturally available to us during speech production, it is less likely integrated with auditory feedback to aid speech monitoring. Future research can alternatively test whether some individuals rely more on proprioceptive feedback from articulators to overcome the disruptive effects of auditory feedback manipulations. To explain the neural substrates of individual variability, we are currently collecting fMRI and DTI data, which we plan to include in our presentation.
Topic Areas: Speech Motor Control, Multisensory or Sensorimotor Integration