Motor Speech Sequence Learning in Adults Who Stutter

Objective Developmental stuttering is a speech disorder characterized by repetition, prolongation, block and disruption of the smooth flow of speech. Environmental, physical, mental, and cognitive-linguistic factors were involved in the initiation and development of stuttering. There have been several theories about the development of stuttering. One of these theories suggests that stuttering is a speech motor control disorder. Based on the speech-motor skills hypothesis, speech production is a motor skill similar to any other (fine) motor skill that humans possess, and the individual motor skills develop from the lowest skill level to the highest level of motor skills. The SMS view suggests that stuttering may arise from limitations in speech motor skill in people who stutter are located more toward the lower end of a presumed normal speech motor skill continuum. Therefore, people who stutter have difficulty learning speech motor skills and have a limited ability to benefit from speech motor practice compared to normal individuals. Many of the stuttering treatment programs teach the new pattern of speech, and the success of these treatment programs depends on the learning of the new speech patterns. So if people who stutter have limited speech motor skills, also will have little success in this treatment programs. Therefore, this study aimed to investigate motor speech sequence learning in adults who stutter. Materials & Methods This was a descriptive-analytical study with participants as 15 adults who stutter and 15 adults who do not stutter. All subjects were matched for age, sex and educational level. The average age was 28.73 for the adults who stutter was 28.4 for the normal people. All of the participants had history of neurological and motor speech disorders. The convenience sampling method was used for this study. The stuttering severity of people who stutter was assessed with Wingate scale and was in moderate range. Participants were asked to repeat an eight syllable non word sequence 30 times during three practice sessions. Recorded samples were analyzed with PRAAT software, and the variables used to measure performance gains included accuracy, response preparation time and sequence duration. The data were statistically analyzed by SPSS software (version 23). Results Based on the findings of the present study, PWS showed improvement in accuracy from day 1 to day 3 (P<0.05), but there was no difference between the two groups in this variable (P>0.05). Also, the reaction time of the PWS improved from day 1 to day 3 (P<0.05), but there was no difference between the two groups (P>0.05). The sequence duration of the PWS improved from day 1 to day 3 (P<0.05) and there was a significant difference between the two groups (P<0.05). According to the results of this study, PWS showed slower sequence duration compare to PNS . Conclusion The results of this study showed that PWS show improvement in accuracy, reaction time and sequence duration variables from day 1 to day 3. Also, PWS show more substantial number of errors compared to PNS, but this difference was not significant between the two groups. Similar results were obtained for the reaction time. Results of this study demonstrated that PWS show slower sequence duration compared to PNS. Some studies suggested that this could be because people who stutter use a control strategy to reduce the number of errors, although many studies suggested that this may indicate motor learning. According to speech motor skills hypothesis, it can be concluded that people who stutter have limitations in motor speech learning abilities. The findings of the present study could have clinical implication for the treatment of stuttering. A B S T R A C T