Precise feedback control underlies sensorimotor learning in speech

2015 ◽  
Vol 113 (3) ◽  
pp. 950-955 ◽  
Author(s):  
Chris Vaughn ◽  
Sazzad M. Nasir

Acquiring the skill of speaking in another language, or for that matter a child's learning to talk, does not follow a single recipe. People learn by variable amounts. A major component of speech learnability seems to be sensing precise feedback errors to correct subsequent utterances that help maintain speech goals. We have tested this idea in a speech motor learning paradigm under altered auditory feedback, in which subjects repeated a word while their auditory feedback was changed online. Subjects learned the task to variable degrees, with some simply failing to learn. We assessed feedback contribution by computing one-lag covariance between formant trajectories of the current feedback and the following utterance that was found to be a significant predictor of learning. Our findings rely on a novel use of information-rich formant trajectories in evaluating speech motor learning and argue for their relevance in auditory speech goals of vowel sounds.

Motor Control ◽  
2011 ◽  
Vol 15 (1) ◽  
pp. 68-84
Author(s):  
Silvia C. Lipski ◽  
Stefanie Unger ◽  
Martine Grice ◽  
Ingo G. Meister

Adult speakers have developed precise forward models of articulation for their native language and seem to rely less on auditory sensory feedback. However, for learning of the production of new speech sounds, auditory perception provides a corrective signal for motor control. We assessed adult German speakers’ speech motor learning capacity in the absence of auditory feedback but with clear somatosensory information. Learners were presented with a nonnative singleton-geminate duration contrast of voiceless, unaspirated bilabial plosives /p/ vs. /pp/ which is present in Italian. We found that the lack of auditory feedback had no immediate effect but that deviating productions emerged during the course of learning. By the end of training, speakers with masked feedback produced strong lengthening of segments and showed more variation on their production than speakers with normal auditory feedback. Our findings indicate that auditory feedback is necessary for the learning of precise coordination of articulation even if somatosensory feedback is salient.


Author(s):  
Wolfram Ziegler

This paper gives an overview of a model that predicts articulation ease for German phonological words on the basis of error data from patients with apraxia of speech (AOS). AOS is introduced as a clinical model of higher order motor processes for articulation. Word production accuracy in AOS is considered as a window into the structure of articulation plans as acquired through speech motor learning in childhood. The NLG model of apraxia of speech is explained. Applications in speech development and adult speech are outlined.


2019 ◽  
Vol 122 (2) ◽  
pp. 552-562 ◽  
Author(s):  
Ayoub Daliri ◽  
Jonathan Dittman

When we produce speech movements, we also predict the auditory consequences of the movements. We use discrepancies between our predictions and incoming auditory information to modify our future movements (adapt). Although auditory errors are crucial for speech motor learning, not all perceived auditory errors are consequences of our own actions. Therefore, the brain needs to evaluate the relevance of perceived auditory errors. In this study, we examined error assessment processes involved in auditory motor adaptation by systematically manipulating the correspondence between speech motor outputs and their auditory consequences during speaking. Participants ( n = 30) produced speech while they received perturbed auditory feedback (e.g., produced “head” but heard a word that sounded like “had”). In one condition, auditory errors were related to participants’ productions (task-relevant errors). In another condition, auditory errors were defined by the experimenter and had no correspondence with participants’ speech output (task-irrelevant errors). We found that the extent of adaptation and error sensitivity (derived from a state-space model) were greater in the condition with task-relevant auditory errors compared with those in the condition with task-irrelevant auditory errors. Additionally, participants with smaller perceptual targets (derived from a categorical perception task) adapted more to auditory perturbations, and participants with larger perceptual targets adapted less. Similarly, participants with smaller perceptual targets were more sensitive to errors in the condition with task-relevant auditory errors. Together, our results highlight the intricate mechanisms, involving both perception and production systems, that the brain uses to optimally integrate auditory errors for successful speech motor learning. NEW & NOTEWORTHY Feedback monitoring is essential for accurate speech production. By providing empirical results and a computational framework, we show that 1) the brain evaluates relevance of auditory errors and responds more to relevant errors, and 2) smaller perceptual targets are associated with more sensitivity to errors and more auditory motor adaptation.


2017 ◽  
Vol 60 (6S) ◽  
pp. 1712-1725 ◽  
Author(s):  
Mara Steinberg Lowe ◽  
Adam Buchwald

Purpose This study investigated whether whole nonword accuracy, phoneme accuracy, and acoustic duration measures were influenced by the amount of feedback speakers without impairment received during a novel speech motor learning task. Method Thirty-two native English speakers completed a nonword production task across 3 time points: practice, short-term retention, and long-term retention. During practice, participants received knowledge of results feedback according to a randomly assigned schedule (100%, 50%, 20%, or 0%). Changes in nonword accuracy, phoneme accuracy, nonword duration, and initial-cluster duration were compared among feedback groups, sessions, and stimulus properties. Results All participants improved phoneme and whole nonword accuracy at short-term and long-term retention time points. Participants also refined productions of nonwords, as indicated by a decrease in nonword duration across sessions. The 50% group exhibited the largest reduction in duration between practice and long-term retention for nonwords with native and nonnative clusters. Conclusions All speakers, regardless of feedback schedule, learned new speech motor behaviors quickly with a high degree of accuracy and refined their speech motor skills for perceptually accurate productions. Acoustic measurements may capture more subtle, subperceptual changes that may occur during speech motor learning. Supplemental Materials https://doi.org/10.23641/asha.5116324


2018 ◽  
Vol 27 (1) ◽  
pp. 37-51 ◽  
Author(s):  
Anita van der Merwe ◽  
Mollie Steyn

Purpose The aim of the study was to propose the speech motor learning approach (Van der Merwe, 2011) as a treatment for childhood apraxia of speech and to determine if it will effect positive change in the ability of a 33-month-old child to produce untreated nonwords and words containing treated age-appropriate consonants (Set 1 sounds), untreated age-appropriate consonants (Set 2), and untreated age-inappropriate consonants (Set 3) and also to determine the nature and number of segmental speech errors before and after treatment. Method An A-B design with multiple target measures and follow-up was implemented to assess the effects of treatment of Set 1. Effect sizes for whole-word accuracy were determined, and two criterion lines were generated following the conservative dual criterion method. Speech errors were judged perceptually. Results Conservative dual criterion analyses indicated no reliable treatment effect due to rising baseline scores. Effect sizes showed significant improvement in whole-word accuracy of untreated nonwords and real words containing age-appropriate treated sounds and real words containing age-appropriate untreated sounds. The number of errors for all three sound sets declined. Sound distortion was the most frequent error type. Conclusions Preliminary evidence suggests potentially positive treatment effects. However, rising baseline scores limit causal inference. Replication with more children of different ages is necessary. Supplemental Materials https://doi.org/10.23641/asha.5596708


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