Vowel Acoustics and Speech Intelligibility in Young Adults With Down Syndrome

Carl, Micalle; Kent, Raymond D.; Levy, Erika S.; Whalen, D. H.

doi:10.1044/2019_jslhr-19-00204

Cited by 9 publications

(13 citation statements)

References 67 publications

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“…The acoustic data supplements the perceptual data by providing objective support for the subjective impressions (Ansel and Kent 1992). This information can guide decision-making for the intervention process by providing insight regarding the nature of the disorder, notably whether the deficit is motor in nature (Carl et al 2020). Furthermore, targeting impaired vowel production within intervention may have a direct positive impact upon speech intelligibility (Lansford and Liss 2014).…”

Section: Discussionmentioning

confidence: 99%

“…Different measures of acoustic vowel space have been applied to dysarthric speech of various aetiologies, including children with developmental dysarthria (Hustad et al 2010), adolescents with Down syndrome (DS; Carl et al 2020), and adults with acquired dysarthria (Fletcher et al 2017), and have demonstrated correlations with speech intelligibility (e.g., in children and adolescents with CP; Higgins andHodge 2002, Liu et al 2005). A review of the literature reveals several common measures that have been applied to the measurement of vowel acoustics in typical and disordered speech.…”

Section: Vowel Acoustics In Developmental Dysarthriamentioning

confidence: 99%

“…Furthermore, in contrast to previously noted measures of vowel centralization, in which a single overall value determines centralization or lack thereof, the VFD provides information regarding the direction (i.e., which vowel/s) from which the centralization occurs. It has been applied thus far in limited instances to speakers with motor speech disorders in which centralization of the vowel space occurred in some, but not all, of the corner vowels (adolescents with DS; Carl et al 2020).…”

Section: Vowel Formant Dispersion (Vfd)mentioning

confidence: 99%

“…Similarly, increasing the number of vowel stimuli per speaker in follow-up studies would allow for additional measures of acoustic vowel space relating to speakers' articulatory proficiency. Specifically, measures of vowel cluster distribution within the acoustic vowel space (McCloy et al 2014, Kent and Vorperian 2018, Carl et al 2020 as well as degree of overlap between vowels (Kim et al 2011) can supplement the current data with insight into speech motor control and predictors of speech intelligibility. Future studies may benefit from inclusion of multi-word stimuli (sentences), in order to consider possible effects of breath control on vowel acoustics and speech intelligibility (Strange et al 2007).…”

Section: Limitations and Future Directionsmentioning

confidence: 99%

“…• VFD: This metric calculates the distance between individual vowel formant values, in the F1 × F2 vowel space, from a weighted centroid, individually for each speaker (Karlsson and van Doorn 2012). The weighted centroid is calculated from the mean of F1 values, while the F2 mean consists only of high-vowel (e.g., /i/ and /u/) F2 values (see Carl et al 2020 for further details of the weighted centroid calculation). This unique placement is noted to be a stronger and have improved placement of the centroid for calculation of vowel dispersion, in contrast to centroids calculated equally from formant means (Karlsson and van Doorn 2012).…”

Section: Vowel Space Metricsmentioning

confidence: 99%

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Acoustic vowel analysis and speech intelligibility in young adult Hebrew speakers: Developmental dysarthria versus typical development

Carl

Icht

2021

Intl J Lang & Comm Disor

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Background: Developmental dysarthria is a motor speech impairment commonly characterized by varying levels of reduced speech intelligibility. The relationship between intelligibility deficits and acoustic vowel space among these individuals has long been noted in the literature, with evidence of vowel centralization (e.g., in English and Mandarin). However, the degree to which this centralization occurs and the intelligibility-acoustic relationship is maintained in different vowel systems has yet to be studied thoroughly. In comparison with American English, the Hebrew vowel system is significantly smaller, with a potentially smaller vowel space area, a factor that may impact upon the comparisons of the acoustic vowel space and its correlation with speech intelligibility. Data on vowel space and speech intelligibility are particularly limited for Hebrew speakers with motor speech disorders. Aims: To determine the nature and degree of vowel space centralization in Hebrew-speaking adolescents and young adults with dysarthria, in comparison with typically developing (TD) peers, and to correlate these findings with speech intelligibility scores. Methods & Procedures: Adolescents and young adults with developmental dysarthria (secondary to cerebral palsy (CP) and other motor deficits, n = 17) and their TD peers (n = 17) were recorded producing Hebrew corner vowels within single words. For intelligibility assessments, naïve listeners transcribed those words produced by speakers with CP, and intelligibility scores were calculated. Outcomes & Results: Acoustic analysis of vowel formants (F1, F2) revealed a centralization of vowel space among speakers with CP for all acoustic metrics of vowel formants, and mainly for the formant centralization ratio (FCR), in comparison with TD peers. Intelligibility scores were correlated strongly with the FCR metric for speakers with CP. Conclusions & Implications: The main results, vowel space centralization for speakers with CP in comparison with TD peers, echo previous cross-linguistic results. The correlation of acoustic results with speech intelligibility carries clinical implications. Taken together, the results contribute to better characterization of the speech production deficit in Hebrew speakers with motor speech disorders. Furthermore, they may guide clinical decision-making and intervention planning to improve speech intelligibility.

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Section: Discussionmentioning

confidence: 99%