Dimensionality Reduction in Lingual Articulation of Vowels: Evidence From Lax Vowels in Northern Anglo-English.

The study focused only on five lax vowels in Northern English; findings may not generalize to tense vowels, diphthongs, or other dialects. The participants were all healthy adults with no history of speech disorders, so the stability of these measures in clinical populations is unknown. The analysis used a single time point (acoustic midpoint) to reduce dynamic movement, which may not fully capture the complexity of tongue gestures in continuous speech. The study relied on DeepLabCut for landmark identification; while validated, errors in automated tracking could influence the results.

The research was funded by the Arts and Humanities Research Council (grant AH/S011900/1). The authors disclosed no other financial support.

Do not interpret the finding that two dimensions are sufficient for vowel contrast as support for using simple two-point clinical measures. The study explicitly states that while two abstract dimensions capture the variance, no single pair of physical measurements reliably replicates this across all vowels and speakers, meaning standard two-point reductions in clinical practice may be systematically biased.