Abstract
This study investigates how native speakers of Najdi and Cairene Arabic perceive the contrast between short and long vowels, focusing on the role of vowel duration. Forty participants (20 per dialect) completed a forced-choice identification task using synthesized minimal pairs with systematically varied vowel durations. Mixed-effects logistic regression models were used to analyze how duration and dialect influenced responses. Duration was a strong predictor of “long” responses across all vowel pairs, but sensitivity to duration varied by dialect and vowel. For [i], Cairene listeners categorized vowels as “long” at shorter durations (84 ms) and showed steeper perceptual slopes than Najdi listeners, who required longer durations (96 ms) and had more gradual responses. For [a], both dialects showed a shared boundary at 101 ms, though Cairene speakers again responded more categorically. For [u], boundary differences were small (Najdi = 100 ms, Cairene = 110 ms) and not statistically significant. These findings suggest that while Arabic speakers rely on duration to distinguish vowel quantity, perceptual calibration is influenced by dialect and vowel quality. The study highlights the value of controlled synthesis and mixed-effects modeling for examining subtle variation in phonemic perception across dialects.
Data availability
The datasets generated during and/or analyzed during the current study are available in the Figshare repository, at the following link: https://figshare.com/s/ae64d72461e07bc08050.
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The author is grateful to the Deanship of Graduate Studies and Scientific Research at the University of Bisha for supporting this work through the Fast-Track Research Support Program.
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Abdullah Alfaifi is the sole author of this paper and was responsible for all aspects of its creation, including the conception, design, data collection, analysis, interpretation, and manuscript preparation.
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This study was reviewed and approved by the Scientific Research Unit at the College of Arts and Letters, University of Bisha (Institutional Review Board). All research procedures involving human participants were conducted in accordance with the Declaration of Helsinki and the institutional guidelines and regulations of the University of Bisha. Ethical approval for the study procedures (recruitment, informed consent, data collection, storage, and analysis) was granted under IRB number UB.24.1.8.ALSRU.1 on 8 January 2024. The approval covered all aspects of the research protocol reported in this manuscript. The study involved no more than minimal risk, ensured equitable selection of participants, and included appropriate measures to protect confidentiality and privacy.
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This study involved adult participants (18 years or older), and written informed consent was obtained from all individuals prior to participation. Written consent was obtained electronically by the principal investigator before participants started the data-collection sessions, between 2 February 2024 and 11 March 2024. Participants were provided with a written information sheet that explained that the project was a research study, described its aims and procedures, outlined any potential risks and benefits (which were minimal), and confirmed that participation was voluntary and that refusal or withdrawal would carry no negative consequences. The information sheet also explained how their data would be handled, including that their responses would be anonymized for analysis, that their anonymity would be assured in any reports or publications, and that any identifiable personal data would be kept confidential, and it stated that anonymized data may be submitted to an online repository and used for journal publication for research purposes only. Participants were informed of their right to withdraw from the study at any time and, where feasible, to request removal of their data after collection. By electronically signing the written consent form, participants indicated that they had read and understood the information provided and agreed to take part under these conditions.
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Alfaifi, A. Perceptual boundary of vowel quantity: a perceptual study of synthesized Arabic vowels. Humanit Soc Sci Commun (2026). https://doi.org/10.1057/s41599-025-06454-8
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DOI: https://doi.org/10.1057/s41599-025-06454-8
