Adaptation to altered feedback in speech

Abstract

This study focuses on how the control of fundamental frequency (F0) of the voice is influenced by modulations of auditory feedback. A methodology analogous to one used in visual perturbation studies of limb movements was used. In these studies, optical feedback is distorted and subjects adapt to the transformed conditions by relearning the spatial coordinates used in visuomotor control. It was investigated whether F0 control would exhibit an analogous adaptation response to altered auditory feedback conditions. Subjects were exposed to pitch-shifted auditory feedback through headphones while producing (a) sustained vowels and (b) sentence material. The F0 feedback was increased in 2 cent steps that were not noticed by the talkers. Both aural- and bone-conducted masking noise were used to minimize feedback from the true F0. During the transformed feedback condition, subjects decreased their pitch in response to the increasing pitch feedback. However, preliminary analyses did not reveal evidence of adaptation to the auditory transformations. This was examined by unexpectedly introducing normal feedback trials to test for ‘‘aftereffects.’’ Results will be discussed in terms of sensorimotor learning and the role of internal models of sensory feedback in speech motor control. [Work supported by NIH NIDCD Grant No. DC-00594 and NSERC.]