Quantitative analysis of voice quality: the influence of the protruded jaw setting on labiodental fricatives

• Main Author: Chan, Junheng
• Other Authors: Scott Reid Moisik
• Format: Thesis-Master by Research
• Language: English
• Published: Nanyang Technological University 2025
• Subjects: Arts and Humanities; Voice quality setting; Phonetic segments; Labiodental fricatives; Dentolabial fricatives; Magnetic resonance imaging (MRI); Principal component analysis (PCA)
• Online Access: https://hdl.handle.net/10356/182790
• Institution: Nanyang Technological University

Existing quantitative research on voice quality settings has focused primarily on interspeech postures (ISPs), which are the vocal tract postures during pauses in speech. It is uncertain whether these ISPs relate to postures used in articulating segmental content. This study addresses this gap by examining how voice quality settings, specifically the protruded jaw (PJAW) setting, influence the articulation of the voiced labiodental fricative [v]. The hypothesis is that a labiodental (LD) articulation is particularly susceptible to the PJAW setting, and will transition into a dentolabial (DL) articulation. The study aims to determine: (1) the articulatory configurations of [v] (or its DL variant) under the PJAW setting, and (2) the extent to which the PJAW setting causes a switch from an LD to DL articulation. Principal component analysis (PCA) is applied to magnetic resonance imaging (MRI) data to analyse pixel intensity variations, condensing these into principal components (PCs) that explain the most variance. Findings reveal that about 31% of LD articulations switch to DL articulations under the PJAW setting. In LD articulations, the upper lip is shortened and it tilts or protrudes outward, while the lower lip is raised. In DL articulations, the upper lip is generally elongated and either points downward or retracts into the oral cavity, while the lower lip is shortened. LD articulations that did not switch are typically associated with a more open jaw, in addition to being protruded, suggesting that an open jaw might be a compensatory adjustment. These results support the principle of susceptibility but also reveal more complex relationships between settings and articulators than previously understood.