Does Learning to Perceive English Vowels Help in Perceiving English Lexical Stress? The Case of Arab Learners of English: A Longitudinal Study

Abstract

This thesis investigates whether there is a relationship between improvement in the perception of English vowels by Arabic speakers and their improvement in the perception of English lexical stress. Previous research showed that L1 vowel inventory affects the cues exploited to contrast L1 vowels. Arabic and English have different vowel inventories. English was found to rely on spectral, temporal, and intrinsic f0 (IF0) cues whereas Arabic is theoretically assumed to rely on its limited spectral cues due to its small number of vowels, in addition to duration and intensity. Of special importance in the perception of English vowels is their intrinsic f0, which along with F1, help in discriminating the different contrasts. Lexical stress locations in Arabic are phonologically determined by syllable weight and position, which makes Arabic a predictable stress language. Concerning the acoustic cues of Arabic stress, production studies have shown that duration and intensity are the two correlates of stress. On the other hand, lexical stress in English is acoustically signalled primarily by f0 in accented stressed syllables. I categorised three main hypotheses in the literature of L2 segmental, prosodic, and phonetic development. These trends either show that L2 learners improve by either reusing their native acoustic cues or features, reweighting their secondary and primary cues, or learning new cues through accessing Universal Grammar (henceforth, UG). In this study, I tested the learning hypothesis. I hypothesised that Arabic learners of English would initially rely on their L1’s limited spectral, durational, and intensity cues to categorise English vowels. With greater exposure to English, they were expected to expand their vowel space, resulting in learning to attune to IF0 as a perceptual cue to English vowels. This newly-learnt cue (i.e., IF0), I hypothesised, would help Arab learners of English to improve their perception of English stress, which is cued by reliance on f0. To test these hypotheses, three perceptual experiments were administered. One experiment tested the perception of the acoustic cues of duration, intensity, and pitch. The other two experiments tested the participants’ identification of stress locations in disyllabic nonsense words, and their discrimination of English vowels. Participants from Libyan, Jordanian, and Sudanese dialects were recruited for this study. The participants were tested twice with an interval of six months between the two phases to monitor their progress. Signal Detection Theory (henceforth, SDT) was used as an analytical tool to gauge the participants’ sensitivities in the different tasks in the two phases of the study. 1 The thesis addressed three questions, all focusing on change over time as represented by the effect of the participants’ sensitivity to individual acoustic cues (i.e., duration, pitch and intensity) on their perception of vowels and stress locations. First, whether the acoustic cues that affected the participants’ perception of vowels in the first phase would differ after six months of exposure to English. Second, whether the effect of the acoustic cues and vowels on the perception of English stress locations would change from their baseline patterns after six months of exposure to native English. Third, and most importantly, whether a relationship existed between improvement over time in the perception of English vowels and improvement in the perception of English stress. Generally, the results of this thesis did not support the learning hypothesis, but gave support to the reweighting hypothesis, which emphasises enhancement and redeployment of existing cues. The results of the first question showed that the learners of all dialects attended to their native perceptual cues of vowels through showing an effect of intensity and duration on vowel perception in Phase One. After six months of exposure to English, they reweighted their cues, exhibiting an effect of only duration when perceiving the same vowels. For the second question, the results broadly showed that the native cue of intensity in addition to vowels affected the perception of stress locations in Phase One, and the same cues affected their perception of stress locations in Phase Two. The main research question was whether there is a relationship between improving the perception of English vowels and improving the perception of English stress. Again, the results showed that the learners’ improvement in the perception of stress was affected by their improvement in the perception of intensity and vowels. This suggests that the learners improved by enhancing their L1 native cues in addition to vowels instead of learning to attend to a new cue, f0.