Temporal organization of syllables in paced and unpaced speech in children and adolescents who stutter.

PURPOSE: Speaking with an external rhythm has a tremendous fluency-enhancing effect in people who stutter. The aim of the present study is to examine whether syllabic timing related to articulatory timing (c-center) would differ between children and adolescents who stutter and a matched control group in an unpaced vs. a paced condition. METHODS: We recorded 48 German-speaking children and adolescents who stutter and a matched control group reading monosyllabic words with and without a metronome (unpaced and paced condition). Analyses were conducted on four minimal pairs that differed in onset complexity (simple vs. complex). The following acoustic correlates of a c-center effect were analyzed: vowel and consonant compression, acoustic intervals (time from c-center, left-edge, and right-edge to an anchor-point), and relative standard deviations of these intervals. RESULTS: Both groups show acoustic correlates of a c-center effect (consonant compression, vowel compression, c-center organization, and more stable c-center intervals), independently of condition. However, the group who stutters had a more pronounced consonant compression effect. The metronome did not significantly affect syllabic organization but interval stability improved in the paced condition in both groups. CONCLUSION: Children and adolescents who stutter and matched controls have a similar syllable organization, related to articulatory timing, regardless of paced or unpaced speech. However, consonant onset timing differs between the group who stutters and the control group; this is a promising basis for conducting an articulatory study in which articulatory (gestural) timing can be examined in more detail.

Reading Fluency in Children and Adolescents Who Stutter.

Speech fluency is a major challenge for young persons who stutter. Reading aloud, in particular, puts high demands on fluency, not only regarding online text decoding and articulation, but also in terms of prosodic performance. A written text has to be segmented into a number of prosodic phrases with appropriate breaks. The present study examines to what extent reading fluency (decoding ability, articulation rate, and prosodic phrasing) may be altered in children (9-12 years) and adolescents (13-17 years) who stutter compared to matched control participants. Read speech of 52 children and adolescents who do and do not stutter was analyzed. Children and adolescents who stutter did not differ from their matched control groups regarding reading accuracy and articulation rate. However, children who stutter produced shorter pauses than their matched peers. Results on prosodic phrasing showed that children who stutter produced more major phrases than the control group and more intermediate phrases than adolescents who stutter. Participants who stutter also displayed a higher number of breath pauses. Generally, the number of disfluencies during reading was related to slower articulation rates and more prosodic boundaries. Furthermore, we found age-related changes in general measures of reading fluency (decoding ability and articulation rate), as well as the overall strength of prosodic boundaries and number of breath pauses. This study provides evidence for developmental stages in prosodic phrasing as well as for alterations in reading fluency in children who stutter.

In Time with the Beat: Entrainment in Patients with Phonological Impairment, Apraxia of Speech, and Parkinson's Disease.

In the present study, we investigated if individuals with neurogenic speech sound impairments of three types, Parkinson's dysarthria, apraxia of speech, and aphasic phonological impairment, accommodate their speech to the natural speech rhythm of an auditory model, and if so, whether the effect is more significant after hearing metrically regular sentences as compared to those with an irregular pattern. This question builds on theories of rhythmic entrainment, assuming that sensorimotor predictions of upcoming events allow humans to synchronize their actions with an external rhythm. To investigate entrainment effects, we conducted a sentence completion task relating participants' response latencies to the spoken rhythm of the prime heard immediately before. A further research question was if the perceived rhythm interacts with the rhythm of the participants' own productions, i.e., the trochaic or iambic stress pattern of disyllabic target words. For a control group of healthy speakers, our study revealed evidence for entrainment when trochaic target words were preceded by regularly stressed prime sentences. Persons with Parkinson's dysarthria showed a pattern similar to that of the healthy individuals. For the patient groups with apraxia of speech and with phonological impairment, considerably longer response latencies with differing patterns were observed. Trochaic target words were initiated with significantly shorter latencies, whereas the metrical regularity of prime sentences had no consistent impact on response latencies and did not interact with the stress pattern of the target words to be produced. The absence of an entrainment in these patients may be explained by the more severe difficulties in initiating speech at all. We discuss the results in terms of clinical implications for diagnostics and therapy in neurogenic speech disorders.