Disfluency in speech and language disorders

Fluency is defined as ‘the ability to speak (…) rapidly and continuously and without any particular effort or thought’ (Starkweather, 1980). This concept is particularly important in the field of language acquisition, both for first and foreign language learning, as well as in speech and language disorders and pathologies. In the case of language acquisition, the above parameters indicate the stage of the language acquisition process. In speech and language disorders, they provide information about the motor system of speech production or the ability to structure a linguistic message.

Disfluencies are observed in all speech production, regardless of age, language, and speaker characteristics. Disfluencies can occur in typical speech as well as in speech and language disorders. In individuals without specific disorders, disfluencies usually signal difficulties with the planning process (i.e. conceptual planning, lexical selection, syntax). Such disfluencies in typical speakers are called hesitations, and they can include pauses, prolongations, or repetitions (Lickley, 2017). Disfluencies can also be one of the symptoms of a speech or language disorder, such as stuttering, cluttering, Parkinson’s disease, Alzheimer’s disease, and many others. Such pathological disfluencies tend to have different characteristics when compared to typical speakers.

Disfluencies in speech and language disorders have long been the focus of linguistic and phonetic studies. Analyses of disfluency frequency, duration, and the type of linguistic and/or phonological structure causing the disfluency provide valuable information about underlying motor or cognitive processes. For example, it has been shown that poorer motor function is associated with the frequency of disfluencies in Parkinson’s disease (Gooch et al., 2023), while lexical retrieval difficulties are thought to be the cause of an increased number of disfluencies in patients with Alzheimer’s disease (Gayraud et al., 2011).

Despite the large number of studies on disfluencies in typical and disordered speech, methods and results are not often aligned between researchers and across disorders. There is little consensus on the terminology used to describe disfluencies. This is the reason we developed this special issue on disfluencies in pathological speech. In it, we bring together studies on pathologies as diverse as Alzheimer’s disease, brain tumours, developmental language delay, and multiple sclerosis, so that the reader can better appreciate the patterns of linguistic disfluencies observed in the speech of these patients.

In their paper on Linguistic disfluencies in Russian-speaking typically and atypically developing children: Individual variability in different contexts, Ingrida Balčiūnenė and Alexandr Kornev describe disfluencies in 6-year-old children with developmental language disorder and matched typically developing children. The authors use structured distributional analysis to establish profiles of disfluency types in these two groups of participants.

Developmental language disorder is also explored by Sveta Fichman and Carmit Altman, in their article on Disfluencies in the narratives of Russian-Hebrew bilingual children with and without Develomental Language Disorder. The paper provides new insights into the significance of the language disorder on the one hand, and the significance of language in a bilingual context on the other, with a focus on disfluency duration and disfluency loci.

Judit Bóna’s article on Pausing and fluency in speech of patients with relapsing-remitting multiple sclerosis investigates the importance of cognitive load on speech fluency in terms of disfluency frequency, disfluency duration, and disfluency type in patients with multiple sclerosis and matched healthy control speakers.

Aurélie Pistono, Jérémie Pariente and Mélanie Jucla compare pathomechanisms of disfluency in two disorders in their study entitled Disfluency patterns in Alzheimer’s disease and frontotemporal lobar degeneration. The authors compare their findings to healthy elderly speakers.

The impact of brain tumours on lexical retrieval is addressed by Malin Antonsson, Kristina Lundholm Fors and Lena Hartelius in their contributed article on Disfluencies in spontaneous speech in persons with low-grade glioma before and after surgery. The study focuses on the difference in the frequency of fillers, false starts, articulation, and speech rate in patients before and after surgery.

The final article entitled Towards an inclusive system for the annotation of (dis)fluency in typical and atypical speech by Ludivine Crible, Ivana Didirková, Christelle Dodane and Loulou Kosmala proposes an inclusive system for disfluency annotation in both typical and disordered speech which can be used with existing annotation software.