Objective:
Vocal hyperfunction (VH) involves excessive and imbalanced laryngeal activity that may influence not only phonation but also articulation. Prior studies have shown that therapeutic techniques can modify vocal tract configuration and articulatory range in VH, but focused only on pre- versus post-treatment changes rather than group-level differences. This study examined whether individuals with VH subtypes—phonotraumatic (PVH) and non-phonotraumatic (NPVH)—differ from those with typical voices in estimated vocal tract length (VTL) and vowel space area (VSA), which index laryngeal height and articulatory working space.
Methods:
Participants included 132 adults in three age- and sex-matched groups of 44 each (27 females, 17 males per group): PVH, NPVH, and controls. Each produced nine vowel-consonant–vowel utterances (/afa/, /ifi/, /ufu/). The first four formants (F1–F4) for /a/, /i/, and /u/ were manually tracked using Praat software. VTL was estimated from F3–F4 using quarter-wavelength and multi-formant equations. VSA was calculated from F1–F2 coordinates of the three corner vowels. An analysis of variance (ANOVA) was first performed to examine the effects of group on VTL. Because VTL can influence VSA, an analysis of covariance (ANCOVA) was also conducted in order to examine the effects of group on VSA while controlling for individual differences in VTL.
Results:
The ANOVA showed that group membership did not have a statistically significant effect on VTL. In contrast, the ANCOVA showed that group did have a statistically significant effect on VSA; post hoc testing found that the PVH group demonstrated significantly smaller VSA values relative to controls.
Conclusion:
Individuals with PVH demonstrated reduced VSA relative to controls, consistent with limited articulatory working space. The absence of group differences in VTL suggests that VSA reduction in PVH reflects constrained tongue and/or lip movements rather than elevated laryngeal position. Findings indicate that the compensatory VH associated with structural vocal fold lesions may impose greater articulatory constraints than the functional muscle tension patterns characteristic of NPVH, highlighting the potential utility of vowel space measures as acoustic markers of VH subtype.