Is "Intrinsic Vowel Duration" Bio-Mechanical or More? Preliminary Results from Northwestern Italian

A well-known property of vowel duration is that it tends to be mediated by vowel height: higher vowels are usually shorter than lower vowels (aka "intrinsic vowel duration"). Results from previous work on a limited number of languages suggest two possible scenarios: (A) vowel duration is entirely driven by the duration of the gesture necessary to reach the tongue height target of the specific vowel, (B) vowel duration targets are part of the cognitive representation of the vowel. However, a third scenario has been put forward theoretically: (C) the duration of the vocalic gesture partially determines vowel duration, but a vowel duration target for each vowel category is also necessary. This study set out to investigate vowel duration data from Northern Italian to assess which of the three scenarios finds support. The first formant frequency (F1) of vowels was used as a proxy for tongue height position, and directed acyclic graph theory was employed to determine the causal relationship between vowel duration, vowel category, and F1. Bayesian modeling results suggest a robust non-linear effect of F1 on vowel duration, together with a direct effect of vowel category, which matches scenario (C).