title: Rapid change in articulatory lip movement induced by preceding auditory feedback during production of bilabial plosives.
abstract: BACKGROUND
  There has been plentiful evidence of kinesthetically induced rapid compensation for unanticipated perturbation in speech articulatory movements. However, the role of auditory information in stabilizing articulation has been little studied except for the control of voice fundamental frequency, voice amplitude and vowel formant frequencies. Although the influence of auditory information on the articulatory control process is evident in unintended speech errors caused by delayed auditory feedback, the direct and immediate effect of auditory alteration on the movements of articulators has not been clarified.
  
  
  RESULTS
  This work examined whether temporal changes in the auditory feedback of bilabial plosives immediately affects the subsequent lip movement. We conducted experiments with an auditory feedback alteration system that enabled us to replace or block speech sounds in real time. Participants were asked to produce the syllable /pa/ repeatedly at a constant rate. During the repetition, normal auditory feedback was interrupted, and one of three pre-recorded syllables /pa/, /Φa/, or /pi/, spoken by the same participant, was presented once at a different timing from the anticipated production onset, while no feedback was presented for subsequent repetitions. Comparisons of the labial distance trajectories under altered and normal feedback conditions indicated that the movement quickened during the short period immediately after the alteration onset, when /pa/ was presented 50 ms before the expected timing. Such change was not significant under other feedback conditions we tested.
  
  
  CONCLUSIONS
  The earlier articulation rapidly induced by the progressive auditory input suggests that a compensatory mechanism helps to maintain a constant speech rate by detecting errors between the internally predicted and actually provided auditory information associated with self movement. The timing- and context-dependent effects of feedback alteration suggest that the sensory error detection works in a temporally asymmetric window where acoustic features of the syllable to be produced may be coded.
authors.affiliation: Human and Information Science Laboratory, NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Atsugi, Kanagawa, Japan. mochida@idea.brl.ntt.co.jp
authors.forename: Takemi
authors.initials: T
authors.lastname: Mochida
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Gomi
authors.forename: Makio
authors.initials: M
authors.lastname: Kashino
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D056228:Feedback, Sensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008046:Lip / Q000502:physiology*; D008297:Male; D009068:Movement; D010700:Phonetics; D010898:Pitch Perception / Q000502:physiology; D011597:Psychomotor Performance; D013060:Speech / Q000502:physiology; D013062:Speech Articulation Tests / Q000379:methods; D013067:Speech Perception / Q000502:physiology*; D013647:Task Performance and Analysis; D013997:Time Factors; D014831:Voice; D055815:Young Adult