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Open Access Knowledge and Scholarship

Date of Award


Culminating Project Type


Degree Name

English: Teaching English as a Second Language: M.A.




College of Liberal Arts

First Advisor

Ettien N. Koffi

Second Advisor

Edward M. Sadrai

Third Advisor

Joy A. McKenzie

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Keywords and Subject Headings

L2 Speech Intelligibility, Vowel Intelligibility, Masking Analysis, Acoustic Phonetics, Arabic-accented English, Just Noticeable Differences


This thesis serves two purposes. The first is to describe Saudi-accented English vowels acoustically. The second is to rely on the measurements obtained from the acoustic phonetic analyses to assess the intelligibility of their vowels. The methodology pioneered by Peterson and Barney (1952) and replicated by Hillenbrand et al. (1995) in their studies of General American English (GAE) is adopted in this study. However, unlike the two previous studies that measured vowels in citation forms, this study measures the acoustic correlates of vowels in running speech style. The participants are 32 Saudi educators who teach English as a Foreign Language (EFL) in the Kingdom of Saudi Arabia: 23 females and 9 males. They were recorded reading a longer version of the GMU Speech Accent Archive text. The analysis focuses on the 11 monophthong phonemic vowel of English. Three different words containing each one of the 11 vowels under consideration were isolated, annotated, and measured for F0, F1, F2, F3, F4, intensity and duration. The software program used is Praat. The annotation and feature extraction were done manually to minimize errors. The first (F1) and second (F2) formants were used to create acoustic vowel spaces. Intelligibility assessments are based on Koffi’s (2019) Acoustic Masking and Intelligibility (AMI) theory. He contends that intelligibility of vowels can be measured instrumentally by comparing the F1 of vowels because this formant carries 80% of the acoustic energy found in vowels. The AMI theory also combines Just Noticeable Differences (JND) thresholds and Relative Functional Load (RFL) calculations to gauge severity of masking and intelligibility. Using this approach, the intelligibility of Saudi-accented vowels is assessed in two ways: internally and externally. Internal masking analyses focus on whether or not Saudi speakers differentiate clearly among the English vowels when they speak. External masking focuses on whether or not the vowels produced by Saudi speakers mask the vowels produced by GAE speakers. The findings discussed in this thesis are based on 7,392 measured tokens. The pedagogical implications and applications recommended in this thesis are data-driven. The most important insights that one can glean from this study is the kiss vowel [ɪ], the foot vowel [ʊ], and the trap vowel [æ] are the most problematic vowels for Saudi speakers of English. Since the RFL of [ɪ] and [æ] are particularly high, it is recommended that the pronunciation of these two vowels be prioritized in instruction.



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