Influence of sublexical frequencies on the speech production in aphasia and apraxia of speech

The aim of this study was to evaluate the influence of sublexical frequencies on the speech production of patients with apraxia of speech and patients with a phonological disorder. Recent studies have discussed syllable frequency as an important parameter which influences phonetically and / or phonologically disturbed speech. In the current investigation frequencies for the units syllable, phoneme, biphoneme, onset and rhyme were evaluated. The focus of our analysis was how the frequencies of the target units relate to those of the units realised by the patients. The results are discussed with regard to the pathomechanisms underlying of apraxia of speech and phonological impairment

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. View Full-Tex

Adaptation

Spoken language is constantly undergoing change: Speakers within and across social and regional groups influence each other’s speech, leading to the emergence and drifts of accents in a language and ultimately to sound change. These processes are driven by mutual unintentional imitation of the phonetic details of others' speech in conversational interactions, suggesting that continuous auditory-motor adaptation takes place in interactive language use and plasticity of auditory-motor representations of speech persists across the lifespan. The brain mechanisms underlying this large-scale social-linguistic behaviour are still poorly understood. This projct aims to investigate the role of cerebellar and striatal dysfunctions in unintended adaptation to the speech rhythm and articulation rate of a second speaker. The study was approved by the ethical committees of the Essen University Hospital (15-6573-BO) and the University of Munich (129-14)