Worse than the dentist: Effects of simultaneous acoustic and somatosensory feedback degradation on speech

Abstract

Speakers use their sensory feedback to monitor real-time speech production; when unexpected changes to that feedback occur, they alter their articulation in immediate, perturbation-specific ways. However, it is not currently known how the feedback from different sensory systems is integrated across contexts. This study varied the reliability of feedback in the auditory and somatosensory domains and examined vowel acoustic phonetics for changes as a result of the manipulation. Acoustic feedback was degraded via eight-channel real-time cochlear implant simulation, while an over-the-counter oral anesthetic (benzocaine) was applied to speakers’ tongues and lips to degrade somatosensory feedback. Speakers (N = 18) produced 139 isolated English words under both baseline and feedback-degraded conditions. F1 and F2 measurements were taken from stressed tokens of eight vowels [i, ɪ, ɛ, ae, ɑ, ʌ, ʊ, u]. Significant differences in speakers’ responses to feedback degradation were observed both across vowels and across...