Validating Spectral Moment Analysis as a Quantitative Measure of Speech Distortions in Speakers With Class III Malocclusions

Abstract

Purpose: This study examined the relationship between judged speech sound distortions and spectral moment metrics in speakers with Class III malocclusion. Method: A quantitative online survey was distributed to 30 speech specialists (clinicians and/or students) and 100 lay listeners to judge the clarity of the sounds /s/, /ʃ/, /t/, and /k/ using a visual analog scale (VAS) from recordings of 11 Class III (underbite) dentofacial disharmony (DFD) patients and eight Class I controls. Patients and controls were grouped according to high, moderate, and low /s/−/ʃ/ first spectral moment differences. A linear mixed model was used to analyze the data. Results: VAS scale ratings increased as a function of decreasing spectral contrast for both groups of listeners. VAS ratings of speech specialists were more homogenous than lay listeners, and speech specialists rated distortions as less severe than lay listeners. Conclusions: Recordings of Class III DFD patients with low /s/−/ʃ/ first spectral moment differences were scored by listeners as having increased VAS scale ratings, indicative of more significant perceived speech-sound distortions. Spectral moment analysis appears to be a promising approach for characterizing speech of DFD patients and other craniofacial disorders. Supplemental Material: https://doi.org/10.23641/asha.19686510

Multitaper Spectrum Analysis of Consonants Produced by Patients With Dentofacial Disharmonies

“…To evaluate the relevance of these acoustic measures for perceptual judgments of speech distortion, we used a set of perceptual judgments collected by Jhingree et al (2022) , which included the consonants /s ʃ t k/ for 25 of the participants whose acoustic data are included in this study (10 Class III closed bite, four Class III AOB, one Class I AOB, and eight Class I controls). The listeners were 30 speech specialists who were asked to rate the level of perceived distortion in the initial consonant of words presented in isolation on a visual analog scale ranging from 0 (completely clear) to 100 (severely distorted).…”

“…Certain consonants are more likely to be affected by different DFDs. Bilabial consonants and sibilants were found to be the most challenging for Class II patients to produce, while Class III patients showed the most difficulty in producing stop and affricate consonants; AOB patients present with the highest prevalence of auditory distortion of fricative consonants ( Jacox et al, 2022 ; Jhingree et al, 2022 ; Keyser et al, 2022 ; Lathrop-Marshall et al, 2022 ; Oliver et al, 2023 ). Grudziąż-Sękowska et al (2018) and Assaf et al (2021) found an association between malocclusion and speech distortion in children.…”