Intelligibility, Articulation Rate, Fluency, and Communicative Efficiency in Typically Developing Children

Abstract

Purpose This article describes the developmental trajectories of four communication-related parameters (i.e., intelligibility, articulation rate, fluency, and communicative efficiency) in a cross-sectional study of typically developing children between 3 and 9 years. The four target parameters were related to auditory-perceptual parameters of speech function. Method One hundred forty-four typically developing children (ages 3;0–9;11 [years;months]; 72 girls and 72 boys) participated. Speech samples were collected using the materials of the Bogenhausen Dysarthria Scales for Childhood Dysarthria, a German assessment tool for childhood dysarthria, and analyzed following established auditory-perceptual criteria on relevant speech functions. To assess intelligibility, naïve listeners transcribed sentences repeated by the children. Articulation rate and fluency were measured by acoustic analyses; communicative efficiency was determined by multiplying the proportion of correctly transcribed syllables by speech rate. Results Intelligibility showed a steep developmental trajectory, with the majority of children obtaining a proportion of intelligible syllables close to 1.0 at the age of 5 years. Articulation rate demonstrated a flatter trajectory, with high variability still within the older children. Disfluencies, on the contrary, occurred only in the youngest children. By definition, communicative efficiency shared the characteristics of intelligibility and rate curves. A principal component analysis revealed, among other findings, strong connections between intelligibility and articulation, as well as between communicative efficiency, articulation, and rate measures. Conclusions While children speak intelligibly, in terms of the applied assessment, at a comparably young age, other communication-relevant parameters show a slower developmental progress. Knowledge on the typical development of communication-related parameters and on their complex relationships with functional speech variables is crucial for the clinical assessment of childhood dysarthria. Supplemental Material https://doi.org/10.23641/asha.14880285

Longitudinal change in speech classification between 4 and 10 years in children with cerebral palsy

“…Notably, recent research suggested that speech intelligibility is still developing for many typically developing children beyond 9 years of age. 27,28 Similarly, studies of speech intelligibility growth in children with CP suggested a very protracted time course, 29 with periods of most rapid growth occurring more than a year later than expected for typical peers. 30,31 Given this growth lag and the protracted course of development among children with and without speech motor impairment, it is important to understand how developmental change translates to ordinal rating scale classification on the VSS and the extent to which early ratings are predictive of later ratings.…”

“…However, speech development differs from other motor development domains. Notably, recent research suggested that speech intelligibility is still developing for many typically developing children beyond 9 years of age 27,28 . Similarly, studies of speech intelligibility growth in children with CP suggested a very protracted time course, 29 with periods of most rapid growth occurring more than a year later than expected for typical peers 30,31 .…”

Intelligibility in Context Scale: Growth Curves for Typically Developing English-Speaking Children Between Ages 2;6 and 9;11

“…Recent research has provided foundational knowledge on speech intelligibility growth trajectories based on transcription intelligibility methods for children between the ages of 2 and 10 years ( Hustad et al, 2020 , 2021 ; Schölderle et al, 2021 ). Transcription intelligibility measures involve recording speech samples from a child, preparing a master transcript of the target words or utterances produced by the child, and having naïve listeners orthographically transcribe the speech recording.…”

Utility of the Intelligibility in Context Scale for Predicting Speech Intelligibility of Children with Cerebral Palsy

“…Until very recently, comprehensive normative standards for characterizing intelligibility development in typical children did not exist. The most recent work, however, has provided a foundation for understanding growth trajectories between the ages of 2 and 10 years [ 8 , 9 , 10 ]. Results have indicated that children’s intelligibility grows rapidly in the preschool years and is highly variable.…”

“…Results have indicated that children’s intelligibility grows rapidly in the preschool years and is highly variable. Intelligibility continues to improve with age throughout middle childhood, and variability decreases with age [ 8 , 9 , 10 ]. Studies of typical speech intelligibility development provide an important foundation for interpreting intelligibility in children with dysarthria.…”