Phonological neighborhood effect in spontaneous speech in adults who stutter.

Purpose: The study examined the relationship between word-form similarity network (phonological neighborhood) and stuttering occurrence in spontaneous speech in adults. The study asked whether neighborhood characteristics, including the number of neighbors (neighborhood density) and the average word frequency among neighbors (neighborhood frequency), differentiate stuttered from fluent words within spontaneous speech samples, and more specifically, whether neighborhood characteristics facilitate speech fluency in adults who stutter.
Method: Spontaneous speech samples were collected from 14 adults who stutter, including 7 with mild stuttering and 7 with severe stuttering. Each stuttered word was matched with a fluently produced word within the sample, controlling for multiple lexical factors. Neighborhood density and neighborhood frequency were compared between the stuttered and matched fluent words.
Results: Adults stuttered on words with lower neighborhood density, compared to fluently produced words, with similar patterns in the two severity subgroups. There appeared to be a marginal difference between single-syllable whole-word repetition and the other stuttering typologies.
Conclusion: Neighborhood density facilitates fluent word production in spontaneous speech in adults who stutter, regardless of stuttering severity. This finding adds to the evidence supporting that phonological encoding plays a role in stuttering in naturalistic, spontaneous speech in adults.
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