Purpose: The purpose of this study was to investigate how ataxia affects the task-dependent role of pitch auditory feedback control in speech. In previous research, individuals with ataxia produced over-corrected, hypermetric compensatory responses to unexpected pitch and formant frequency perturbations in auditory feedback in sustained vowels and single words (Houde et al., 2019; Li et al., 2019; Parrell et al., 2017). In this study, we investigated whether ataxia would also affect the task-dependent role of the auditory feedback control system, measuring whether pitch-shift responses would be mediated by speech task or semantic focus pattern as they are in neurologically healthy speakers.
Methods: Twenty-two adults with ataxia and 29 age- and sex-matched control participants produced sustained vowels and sentences with and without corrective focus while their auditory feedback was briefly and unexpectedly perturbed in pitch by +/-200 cents. The magnitude and latency of the reflexive pitch-shift responses were measured as a reflection of auditory feedback control.
Results: Individuals with ataxia produced larger reflexive pitch-shift responses in both the sustained-vowel and sentence-production tasks than the control participants. Additionally, a differential response magnitude was observed by task and sentence focus pattern for both groups.
Conclusion: These findings demonstrate that even though accuracy of auditory feedback control correction is affected by cerebellar damage, as evidenced by the hypermetric responses, the system still retains efficiency in utilizing the task-dependent role of auditory feedback.
Keywords: ataxia; cerebellum; dysarthria; pitch; speech language pathology; voice.