A reevaluation of vowel length and lengthening in modern standard Persian

Abstract

This study reexamines the phonetic and phonological status of vowel length in Modern Standard Persian (MSP). Persian has undergone significant changes across its development. The preceding era, Middle/Pahlavi Persian, maintained a quantity-based vowel system in which length distinctions were phonetically and phonologically active. These historical distinctions have been reanalyzed as distinctions between two sets of vowels [a, e, o] and [ɑ, i, u] in contemporary MSP (e.g., Rahbar, 2008; Windfuhr, 2009). Previous studies report conflicting results regarding durational differences between these sets in MSP (e.g., Modarresi Ghavami, 2011; 2015; Sama’i, 2019; Aronow et al., 2017). However, the phonological distinction is widely argued to be observable in the context of compensatory lengthening (CL) triggered by glottal coda deletion, which is claimed to apply only to historically short vowels [a, e, o] and not to historically long vowels [ɑ, i, u] due to their bimoraic structure (Hayes, 1989; Darzi, 1991; Kambuzia & Hadian, 2009; Azizian & Kambuzia, 2018). To address these phonetic disagreements and reassess the phonological claim, this study reports on a production experiment with three native speakers of MSP, controlling for phonological and prosodic environments and speech rate. Results show that vowel length distinctions between the two sets were statistically significant and consistent across contexts, confirming that phonetic length remains active in MSP. However, contrary to prior literature, CL was observed across all six vowels, including historically long ones, though with weaker effects for one vowel. This finding challenges the prevailing claim that CL provides direct evidence for a categorical moraic asymmetry between historically short and long vowels. These results suggest that MSP is in a state of transition from a primarily quantity-based system to a primarily quality-based one. This study refines the description of MSP’s vowel system and provides new evidence against widely held assumptions in the literature regarding the phonological conditioning of CL.