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Research Article
Speech Naturalness in the Assessment of
Childhood Dysarthria
Theresa Schölderle,
a
Elisabet Haas,
a
and Wolfram Ziegler
a
a
Institute for Phonetics and Speech Processing, Ludwig-Maximilians-Universität München, München, Germany
AR T I CLE I N F O
Article History:
Received January 23, 2023
Revision received March 23, 2023
Accepted April 7, 2023
Editor-in-Chief: Katherine C. Hustad
Editor: Ignatius Nip
https://doi.org/10.1044/2023_AJSLP-23-00023
Correspondence to Theresa Schölderle: theresa.schoelderle@ekn-
muenchen.de. Disclosure: The authors have declared that no competing
financial or nonfinancial interests existed at the time of publication.
AB ST R A C T
Purpose: This study investigated perceived speech naturalness estimated by
adult listeners in typically developing children and children with dysarthria. We
aimed to identify predictors of naturalness among auditory-perceptual parame-
ters and to evaluate the concept of naturalness as a clinical marker of childhood
dysarthria.
Method: In a listening experiment, naive adult listeners rated speech natural-
ness of 144 typically developing children (3–9 years old) and 28 children with
neurological conditions (5–9 years old) on a visual analog scale. Speech sam-
ples were recorded using the materials of the Bogenhausen Dysarthria Scales–
Childhood Dysarthria, which also provides for auditory-perceptual judgments
covering all speech subsystems.
Results: Children with dysarthria obtained significantly lower naturalness ratings
compared to typically developing children. However, there was a substantial
age effect observable in the typically developing children; that is, younger typi-
cally developing children were also perceived as somewhat unnatural. The rat-
ings of the typically developing children were influenced by the occurrence of
developmental speech features; for the children with neurological conditions,
specific symptoms of dysarthria had an additional effect. In both groups, the
perception of naturalness was predominantly determined by the children’s artic-
ulation and intelligibility.
Conclusions: Both symptoms of childhood dysarthria and developmental
speech features (e.g., regarding articulation and intelligibility) were associated to
some extent with unnatural speech by the listeners. Thus, perceived speech
naturalness appears less suitable as a marker of dysarthria in children than in
adults.
Dysarthria is a speech disorder that can be caused
by various neurological conditions and may affect adults
(e.g., with stroke or Parkinson’s disease) as well as chil-
dren (e.g., with cerebral palsy [CP] or genetic syndromes).
By definition, dysarthria is characterized by impairments
of the speech motor subsystems, that is, respiration, pho-
nation, articulation, and prosody (Duffy, 2020). Clinical
assessment is predominantly focused on the speech charac-
teristics directly associated with these motor impairments
(e.g., impaired voice quality, articulatory dysfunction), but
for a comprehensive and ecologically valid description of
the speech disorder, the manifold and highly individual
consequences of the disorder for everyday communication
must also be considered (International Classification of
Functioning, Disability and Health; World Health Organi-
zation, 2001).
So far, research on communication-related parame-
ters both in adults and children with dysarthria has pre-
dominantly focused on speech intelligibility. In adults, sev-
eral studies also addressed perceived speech naturalness,
showing that this concept may add relevant detail to the
picture of communication abilities in dysarthria (Dagenais
& Wilson, 2002; Dagenais et al., 2006; Klopfenstein et al.,
2020; Schölderle et al., 2016; Southwood & Weismer,
1993; Yorkston et al., 1990). Speech naturalness refers to
a rather broad perceptual impression representing the
American Journal of Speech-Language Pathology Vol. 32 1633–1643 July 2023 Copyright © 2023 American Speech-Language-Hearing Association 1633