Foot duration and polysyllabic shortening among Arab speakers of English

1. INTRODUCTION

The acquisition of second language (L2) prosody is of crucial importance for intelligibility and perceptions of foreign accentedness (Flege, Munro, & MacKay, 1995Flege, J., Takagi, N., & Mann, V. (1995). Japanese adults can learn to produce English /ɻ/ and /l/. Language and Speech, 38, 25-55.
; Tajima, Port, & Dalby, 1997Tajima, K., Port, R., & Dalby, J. (1997). Effects of speech timing on intelligibility of foreign accented English. Journal of Phonetics, 25(1), 1-24
; White & Mattys, 2007White, L., & Mattys, S. (2007). Calibrating rhythm: First language and second language studies. Journal of Phonetics, 35(4), 501-522. http://dx.doi.org/10.1016/j.wocn.2007.02.003
). One neglected aspect of L2 prosody is polysyllabic shortening (PS). PS refers to the phenomenon where vowels, especially stressed vowels, become shorter the more syllables are added to the stem, e.g., the vowel in ‘stick’ is longer than the vowel in ‘sticky’ (Lehiste, 1972Lehiste, I. (1972). The timing of utterances and linguistic boundaries. Journal of the Acoustical Society of America, 51(6B), 2018-2024. http://dx.doi.org/10.1121/1.1913062
). This contributes to the perception of a stress-timed rhythm where interstress intervals tend to be regular (Lehiste, 1977Lehiste, I. (1977). Isochrony reconsidered. Journal of Phonetics, 5(3), 253-263.‏ http://dx.doi.org/10.1016/S0095-4470(19)31139-8
; Kim & Cole, 2005Kim, H., & J. Cole (2005). The stress foot as a unit of planned timing: Evidence from shortening in the prosodic phrase. In Proceedings of Interspeech 2005, Lisbon, 2005, pp. 2365-2368. http://dx.doi.org/10.21437/Interspeech.2005-37
; see Turk, 2012Turk A. (2012) The temporal implementation of prosodic structure. In A. Cohn, C. Fougeron, M Huffman (Eds.). The Oxford Handbook of Laboratory Phonology (pp. 242- 253). Oxford, UK: Oxford University Press.
, for more details).

Unlike the well-established PS in English, little is known about it in Arabic, which does not seem to use it as much as English does. Most earlier research on the development of the interlanguage (IL) of Arab learners of English focused on segmental aspects and to a lesser degree on suprasegmental aspects including syllable structure, stress, and intonation; however, to the best of our knowledge, no study has tackled PS in the IL of Arab learners. How PS is used by speakers whose first language (L1) is syllable-timed (like Arabic) where PS does not seem to be as evident as in stress-timed languages such as English (see Abu Guba, Mashaqba & Huneety, 2023bAbu Guba, M. N., Mashaqba, B., & Huneety, A. (2023b). Polysyllabic shortening in Modern Standard Arabic. Journal of Semitic Studieshttp://dx.doi.org/10.1093/jss/fgac030
) is not clear. We therefore predict that Arab speakers of English will not apply the same degree of PS adopted by English speakers.

The importance of investigating phenomena such as PS is threefold. First, speech timing contributes to making speech more understandable (Ordin & Polyanskaya, 2014Ordin, M., Polyanskaya, L. (2014). Development of timing patterns in first and second languages. System, 42, 244-257. http://dx.doi.org/10.1016/j.system.2013.12.004
; Turk & Shattuck-Hufnagel, 2013Turk A, & Shattuck-Hufnagel S. (2013). What is speech rhythm? A commentary inspired by Arvaniti & Rodríguez, Krivokapic´, & Goswami & Leong. Laboratory Phonology, 4, 93-118. http://dx.doi.org/10.1515/lp2013-0005
). Second, it plays a crucial role in the perception of a foreign accent as lack of durational variation results in a perception of foreign-accentedness (Polyanskaya, Ordin, & Ulbrich, 2013Polyanskaya, L., Ordin, M., & Ulbrich, C. (2013). Contribution of timing patterns into perceived foreign accent. In ). P. Wagner (Ed.), Proceedings of Elektronische Sprachsignalverarbeitung (ESSV) (pp. 197-204). Dresden: TUDpress.
). It has been reported that Jordanian Arab teachers of English were perceived to speak with a fairly strong foreign accent, despite their long experience and use of English (e.g., Abu Guba, Mashaqba, Hneety, & Hajeid, 2021Abu Guba, M. N., Mashaqba, B., Huneety, A. & Hajeid, O. (2021). Attitudes toward Jordanian Arabic-accented English among native and non-native speakers of English. ELOPE: English Language Overseas Perspectives and Enquiries, 18(2), 1-29. http://dx.doi.org/10.4312/elope.18.2.9-29
; Abu Guba, Daoud & Jarbou, 2023Abu Guba, M. N., S. Daoud & S. Jarbou. (2023). Foreign accented-speech and perceptions of confidence and intelligence. Journal of Psycholinguistic Research. doi: 10.1007/s10936-023-09940-9.
). One reason behind this could be the lack of durational variation and PS in their speech. Third, acquiring English rhythmic patterns constitutes a major challenge to English learners including those whose L1 is stress-timed with high durational variability (Ordin, Polyanskaya, & Ulbrich, 2011Ordin, M., Polyanskaya, L., Ulbrich, C. (2011). Acquisition of timing patterns in second language. Proceedings of Interspeech 2011, 1129-1132. http://dx.doi.org/10.21437/Interspeech.2011-336
). This study therefore aims to explore the extent to which non-native speakers (NNSs) of English whose L1 is not as stress-timed as English will acquire the mechanisms of PS. The study is thus intended to be a contribution to the study of IL rhythm. It will shed light on the development of PS and the extent to which it is transferable (cf. Ordin & Polyanskaya, 2014Ordin, M., Polyanskaya, L. (2014). Development of timing patterns in first and second languages. System, 42, 244-257. http://dx.doi.org/10.1016/j.system.2013.12.004
). This will enhance our understanding of speech rhythm in general and its interactions in L1 and L2.

The present study will attempt to answer the following questions:

It is expected that foot duration produced by NNSs will be different from that of NSs; the higher the level of the NNSs, the more native-like their performance will be. Also, it is more likely that foot duration among the NNSs will depend on the number of segments and syllables within a foot.

2. BACKGROUND

Earlier studies on PS in English found that stressed syllables tend to become shorter the more syllables are added to the stem (e.g., Lehiste, 1972Lehiste, I. (1972). The timing of utterances and linguistic boundaries. Journal of the Acoustical Society of America, 51(6B), 2018-2024. http://dx.doi.org/10.1121/1.1913062
; Port, 1981Port, R. F. (1981). Linguistic timing factors in combination. Journal of the Acoustical Society of America, 69(1), 262-274. http://dx.doi.org/10.1121/1.385347
; White & Turk, 2010White, L., & Turk, A. E. (2010). English words on the Procrustean bed: Polysyllabic shortening reconsidered. Journal of Phonetics, 38(3), 459-471. http://dx.doi.org/10.1016/j.wocn.2010.05.002
). It was also found that PS was more evident in pitch-accented vowels than unaccented ones (e.g., Kim & Cole, 2005Kim, H., & J. Cole (2005). The stress foot as a unit of planned timing: Evidence from shortening in the prosodic phrase. In Proceedings of Interspeech 2005, Lisbon, 2005, pp. 2365-2368. http://dx.doi.org/10.21437/Interspeech.2005-37
; White & Turk, 2010White, L., & Turk, A. E. (2010). English words on the Procrustean bed: Polysyllabic shortening reconsidered. Journal of Phonetics, 38(3), 459-471. http://dx.doi.org/10.1016/j.wocn.2010.05.002
). This type of shortening was generally believed to be a component of the stress-timed rhythm of English in that it results in more similar foot duration with regular timing between interstress intervals (Lehiste, 1972Lehiste, I. (1972). The timing of utterances and linguistic boundaries. Journal of the Acoustical Society of America, 51(6B), 2018-2024. http://dx.doi.org/10.1121/1.1913062
; Port, 1981Port, R. F. (1981). Linguistic timing factors in combination. Journal of the Acoustical Society of America, 69(1), 262-274. http://dx.doi.org/10.1121/1.385347
).

However, other researchers argued that vowel shortening could also be related to several factors including word-initial/final lengthening, accentual lengthening, and demarcating prosodic boundaries (Beckman & Edwards, 1990Beckman, M. E., & Edwards, J. (1990). Lengthenings and shortenings and the nature of prosodic constituency. In J. Kingston, & M. E. Beckman (Eds.), Papers in Laboratory Phonology I: Between the Grammar and the Physics of Speech (pp. 152-178). Cambridge: Cambridge University Press.
; Turk & White, 1999Turk, A. E., & White, L. (1999). Structural influences on accentual lengthening in English. Journal of Phonetics, 27(2), 171-206. http://dx.doi.org/10.1006/jpho.1999.0093
; Turk & Shattuck-Hufnagel, 2000Turk, A. E., & Shattuck-Hufnagel, S. (2000). Word-boundary-related duration patterns in English. Journal of Phonetics, 28(4), 397-440. http://dx.doi.org/10.1006/jpho.2000.0123
; White & Turk, 2010White, L., & Turk, A. E. (2010). English words on the Procrustean bed: Polysyllabic shortening reconsidered. Journal of Phonetics, 38(3), 459-471. http://dx.doi.org/10.1016/j.wocn.2010.05.002
). Syllables in word-initial position tend to be longer than their counterparts in non-initial position. For example, the diphthong in the monosyllabic word ‘choir’ will be longer than that in ‘acquire’, all other things being equal, due to the effects of initial lengthening. Similarly, final lengthening could increase the duration of the vowel in the monosyllabic word ‘tune’, when it is word-final, but not in the disyllable ‘tuna’, as the long vowel will not be in word-final position and therefore less affected by final lengthening (Turk & Shattuck-Hufnagel, 2000Turk, A. E., & Shattuck-Hufnagel, S. (2000). Word-boundary-related duration patterns in English. Journal of Phonetics, 28(4), 397-440. http://dx.doi.org/10.1006/jpho.2000.0123
).

Accentual lengthening, where segments receiving a pitch-accent/phrasal stress undergo lengthening (White & Turk, 2010White, L., & Turk, A. E. (2010). English words on the Procrustean bed: Polysyllabic shortening reconsidered. Journal of Phonetics, 38(3), 459-471. http://dx.doi.org/10.1016/j.wocn.2010.05.002
), is greater in a monosyllable than in a disyllable, as in ‘knee’ and ‘kneecap’ (Turk & White, 1999Turk, A. E., & White, L. (1999). Structural influences on accentual lengthening in English. Journal of Phonetics, 27(2), 171-206. http://dx.doi.org/10.1006/jpho.1999.0093
). Furthermore, Turk and Shattuck-Hufnagel (2000)Turk, A. E., & Shattuck-Hufnagel, S. (2000). Word-boundary-related duration patterns in English. Journal of Phonetics, 28(4), 397-440. http://dx.doi.org/10.1006/jpho.2000.0123
reported that PS was greater in pitch-accented words, an indication that accentual lengthening and PS are interrelated. White and Turk (2010)White, L., & Turk, A. E. (2010). English words on the Procrustean bed: Polysyllabic shortening reconsidered. Journal of Phonetics, 38(3), 459-471. http://dx.doi.org/10.1016/j.wocn.2010.05.002
suggested that PS observed in polysyllabic words might result from different degrees of accentual lengthening where it is highest in monosyllables but attenuates in polysyllabic words. A third possible reason behind PS is related to signaling word boundaries. Evidence for using PS as a cue to prosodic boundaries comes from languages with fixed word-initial stress such as Estonian and Finnish. In these languages PS tends to be inexistent because prosodic boundaries are already signaled by primary stress, and therefore there is no need to use vowel length to demarcate word edges (Suomi, 2007Suomi, K. (2007). On the tonal and temporal domains of accent in Finnish. Journal of Phonetics, 35(1), 40-55. http://dx.doi.org/10.1016/j.wocn.2005.12.001
).

Although these factors suggest that PS can be related to aspects other than stress-timing, they do not refute the contention that PS can also be related to stress-timing tendencies. The purpose of this study is not to explain why this shortening happens; rather it aims to find the extent to which Jordanian Arab NNSs of English apply vowel shortening in their ILs.

Very few studies investigated PS in the IL of English NNSs. Krivokapic (2013)Krivokapic, J. (2013). Rhythm and convergence between speakers of American and Indian English. Laboratory Phonology, 4 (1), 9-65. http://dx.doi.org/10.1515/lp-2013-0003
comparing four American NSs with four Indian speakers of English as an L2, found that the Indian speakers, who used English all their lives, employed PS in an English nativelike manner. No sufficient information about the participants was available to know the degree of their bilingual status, which casts doubt on the validity of the results. Dealing with bilinguals rather than foreign language speakers, Gibson and Summers (2018)Gibson, T. A., & Summers, C. (2018). Polysyllabic shortening in speakers exposed to two languages. Bilingualism: Language & Cognition, 21(3), 471-478. http://dx.doi.org/10.1017/S1366728918000068
compared the use of PS in English and Spanish by a group of English monolinguals and a group of balanced bilinguals in English and Spanish repeating nonwords in the two languages. They found that the English monolinguals did not implement English PS when repeating the Spanish nonwords, while the bilingual group used a degree of PS that was appropriate with the language in question. Both groups produced more PS in English than in Spanish, which is a syllable-timed language. To account for the lack of transfer of English timing patterns into Spanish (which was expected as the English monolinguals’ level in Spanish was limited, as adults), the researchers argued that this unanticipated finding could relate to the group’s early exposure to Spanish (around age 4), an exposure that could have given them the ability to acquire motor plans that might have prevented transfer of PS from L1 to L2. This does not seem to be the case. It seems that PS, which is a characteristic of stress-timed rhythms, does not transfer to L1s with syllable-timed rhythms at beginning levels as it is a marked feature and L2 learners start with a syllable-timed rhythm regardless of their L1 rhythm class, most probably due to lack of adequate articulatory control, which improves as L2 proficiency increases (Ordin & Polyanskaya, 2014Ordin, M., Polyanskaya, L. (2014). Development of timing patterns in first and second languages. System, 42, 244-257. http://dx.doi.org/10.1016/j.system.2013.12.004
).

In another study tackling PS among bilingual children, Gibson & Bernales (2019)Gibson, T. A. & Bernales, C. (2019). Polysyllabic shortening in Spanish-English bilingual children. International Journal of Bilingualism, 24(2), 437-454. http://dx.doi.org/10.1177/1367006919846426
compared PS in Spanish and English bilingual children with that in monolingual Spanish and English ones. They found that both groups implemented PS similarly although Spanish is syllable-timed, while English is stress-timed. They argued that lack of differences between the groups could be attributed to a universal phonetic constraint whereby speakers use one puff of air to produce a string of segments and these segments tend to be shorter the more segments or syllables there are (Quené, 2008, p. 1109)Quené, H. (2008). Multilevel modeling of between-speaker and within-speaker variation in spontaneous speech tempo. Journal of the Acoustical Society of America, 123(2), 1104-1113. http://dx.doi.org/10.1121/1.2821762
.

Studies dealing with the acquisition of polysyllabic shortening by Arabic speakers of English are lacking. Moreover, previous studies dealing with timing patterns in Arabic and the ILs of Arabic speakers of English are rather limited. Abu Guba, Mashaqba, Jarbou & Al-Haj Eid (2023c)Abu Guba, M. N., Mashaqba, B., Jarbou, S. & Al-Haj Eid, O. (2023c). Production of vowel reduction among Jordanian Arab learners of English: Acoustic investigation. Poznan Journal of Contemporary Linguistics. https://doi.org/10.1515/psicl-2022-2011.
compared the degree of vowel reduction as produced by Jordanian Arab speakers of English and English NSs. They found that the Jordanian NNSs of English, even the advanced ones, failed to produce English reduced vowels in a native-like manner. Although the Jordanian NNSs were aware that the reduced vowels were unstressed, they did not reduce the duration of the reduced vowels, which were significantly much longer than those produced by the English NSs. These findings seem to suggest that Jordanian Arabic speakers do not use durational variation in their speech as much as English NSs do. This seems to be related to the mechanisms of Arabic speech rhythm, which is clearly different from that of English (Abu Guba, Fareh & Yagi, 2023aAbu Guba, M. N., Fareh, S. & Yagi, S. (2023a). Arabic and English speech rhythms: A contrastive review. International Journal of Arabic and English Studies. Volume 23, Issue 1, Pages 183 - 202. doi: 10.33806/ijaes2000.23.1.10
). Put differently, it could be the case that the syllable-timed Jordanian Arabic speech rhythm results in less variation in timing patterns where vowel duration tends to be similar in feet regardless of their segmental make-up.

This study will further investigate timing patterns by examining the extent to which Jordanian Arabic speakers use PS in their ILs. This will shed more light on Arabic speech rhythm and its mechanisms and on the nature of PS in general. Is PS a phonetic universal and to what extent is it related to the speech rhythm of a language?

3. METHODS

4. RESULTS AND DISCUSSION

Results show that there were clear differences between the NSs and the NNSs, but negligible differences between the two NNSs’ groups. In this section, we first compare the duration of feet across the three groups, and then we compare the vowel duration in the three types of words as produced by the three groups.

4.1. Foot duration

 ⌅

The NSs exhibited less variation in foot length than did the NNSs, with feet becoming longer the more segments were added to the foot (Figures 1 and 2). NSs’ feet in monosyllabic words were 367.3 ms; in disyllabic words, 402; and in trisyllabic words, 553 ms. That is, disyllabic feet were 35 ms longer than monosyllabic feet and trisyllabic feet were 186 ms longer than monosyllabic ones. This runs against the isochrony view of feet in English (e.g., Abercrombie, 1967Abercrombie, D. (1967). Elements of General Phonetics. Edinburgh: Edinburgh University Press.
). Rather, these results lend support to the view that similar foot duration in English, which is a stress-timed language, is a tendency such that syllables do not have the same duration, with stressed syllables being longer than unstressed ones, and compression of syllables applying the more syllables there are in a foot (see Roach, 1982Roach, P. (1982). On the distinction between “stress-timed” and “syllable-timed” languages. In D. Crystal (Ed.), Linguistic Controversies (pp. 73-79). London: Arnold.
; Dauer, 1983Dauer, R. M. (1983). Stress-timing and syllable-timing reanalyzed. Journal of Phonetics, 11(1), 51-62. http://dx.doi.org/10.1016/S0095-4470(19)30776-4
).

Foot duration among the NNSs exhibited more variation as shown in figure 1. Although monosyllabic feet were close to the ones produced by the NSs, disyllabic and trisyllabic feet were considerably longer across the two groups of NNSs. Disyllabic and trisyllabic feet produced by the advanced group were about 75 and 91 ms, respectively, longer than those of NSs. Similarly, the intermediate group produced disyllabic and trisyllabic feet that were 88 and 108 ms, respectively, longer than feet produced by the NSs. Differences between the advanced and the intermediate groups were much smaller: 13 ms between disyllabic feet and 17 ms between trisyllabic feet. A mixed model ANOVA comparing foot duration across the three groups with the number of syllables as a fixed factor and word as a random factor, controlling for speaker and gender revealed a main effect for the interaction of group and number of syllables (F(4, 4.256) = 27.264, p = .003, η_p ²= 96, power = 1). Bonferroni post-hoc tests revealed that the differences between all the groups were significant; p was < .001 for all the differences between the NS and NNS groups while it stood at .033 for the difference between the advanced and the intermediate groups.

Figure 1.  Foot duration across the three groups.

Figure 2.  Foot duration according to number of syllables across the three groups.

This shows that the NNSs produced much longer feet the more segments were added, which suggests that their IL is more syllable-timed than stress-timed, and they do not seem to use PS as much as the English NSs do (discussed in the following subsection).

4.2. Polysyllabic shortening

 ⌅

In this subsection, we first compare the duration of the long vowel across the three groups and then we compare the percentages of the long vowel in the whole word to give a clearer picture and provide more evidence on PS across the three groups.

4.2.1. Long vowel duration

 ⌅

Figures 3 and 4 give details on the duration of long vowels in monosyllabic, disyllabic and trisyllabic words. Overall, the vowel becomes shorter the longer the word is across the three groups; however, clear differences were attested among the NSs and the NNSs in the realization of long vowels in polysyllabic words.

Figure 3.  Long vowel duration across the three groups.

Figure 4.  Long vowel duration according to number of syllables across the three groups.

Mean vowel length in monosyllabic words was very close across the three groups (around 150 ms). However, clear differences among the three groups in producing disyllabic and trisyllabic feet were attested. NSs produced shorter vowels in disyllabic feet (100 ms) and even shorter ones in trisyllabic feet (87 ms). The long vowel was 50 ms (33%) shorter in disyllables than in monosyllables and 13 ms (13%) shorter in trisyllables than in disyllables. This shows that NSs apply polysyllabic shortening, which is in harmony with the literature on PS in English (cf. Section 1).

By contrast, the NNSs did not shorten their vowels considerably in longer words with less than a 7-ms difference between vowels in monosyllabic feet and polysyllabic feet across both groups. Moreover, the vowels in polysyllabic words across the two NNS’ groups were much longer than those produced by the NSs (about 42 ms longer in disyllabic words and 52 ms longer in trisyllabic words), although the differences between the three groups in producing the long vowels in monosyllabic words were too small. The differences between the advanced and the intermediate groups were rather small: the long vowel in disyllables produced by the intermediate group was 12 ms longer than that produced by the advanced group, and the long vowel in trisyllabic feet produced by the intermediate group was 6 ms longer than that realized by the advanced group.

A mixed model ANOVA comparing vowel length across the three groups with the number of syllables as a fixed factor and word as a random factor, controlling for speaker and gender, revealed a main effect only for the interaction of group and number of syllables (F(4, 3.583) = 24.245, P = .007, η_p ²= 96, power = .98). Bonferroni post-hoc tests revealed that the differences between the NS group on the one hand, and the advanced and the intermediate groups on the other hand, were significant (p < .001). However, the differences between the advanced and the intermediate groups were not significant (p = .151).

4.2.2. Percentages of the long vowel in the whole word

 ⌅

To control for tempo effects, we compare the percentages of the long vowel in the different words in this section. This is necessary as the differences in the previous section might be affected negatively by speaking rates that can be different across and within speakers. Figures 5 and 6 below show that the mean percentages of the long vowel in the whole word in monosyllabic words across the three groups were very close (around 40%). However, clear differences between the NS group and the other NNS groups with respect to the percentages in disyllabic and trisyllabic feet were attested, but very small differences between the NNS groups were attested. Although the advanced and the intermediate groups reduced the percentages of their vowels in disyllabic and trisyllabic words, their percentages were still higher than those of the NS group. They were 5% and 7% higher in disyllabic words, respectively, and about 7% higher in trisyllabic words for both groups. The differences between the advanced and the intermediate groups were less than 2%.

Figure 5.  Percentages of long vowels in the whole word across the three groups.

Figure 6.  Percentages of long vowels according to the number of syllables across the three groups

A mixed model ANOVA comparing the vowel percentages across the three groups with the number of syllables as a fixed factor and word as a random factor, controlling for speaker and gender, revealed a main effect for group (F(2, 8.329) = 5.228, P = .034, ηp2= 56, power = .67), and for the number of syllables (F(2, .823) = 655.821, P = .048, ηp2= 99, power = .72), but not for the interaction between groups and syllables (p= .615). This is because the differences between the three groups with respect to monosyllabic words were marginal, and the differences between the advanced and the intermediate groups were also very small. Bonferroni post hoc tests revealed that only the differences between the NS group on the one hand, and the other two NNS groups, on the other hand, were significant, while the differences between the two NNS groups were not significant (p= .494).

Taking all the results together, we can clearly see that the NNS groups do not use PS as much as the NS group do, an indication that the NNSs’ IL tends to be less stress-timed, and the NNSs have not acquired the stress-timed rhythm of the English language. This is in line with Abu Guba et al.’s (2023b)Abu Guba, M. N., Mashaqba, B., & Huneety, A. (2023b). Polysyllabic shortening in Modern Standard Arabic. Journal of Semitic Studieshttp://dx.doi.org/10.1093/jss/fgac030
finding that the degree of PS in Modern Standard Arabic (the formal variety in Arabic) as produced by Jordanian speakers is not comparable to that in English; Jordanian speakers produced vowels in disyllabic words and trisyllabic words with similar durations, but the vowels were shorter than in monosyllabic words.

Moreover, the present study’s findings do not agree with Gibson and Bernales (2019)Gibson, T. A. & Bernales, C. (2019). Polysyllabic shortening in Spanish-English bilingual children. International Journal of Bilingualism, 24(2), 437-454. http://dx.doi.org/10.1177/1367006919846426
, who argued that PS could arise from a universal phonetic constraint that requires a faster articulation rate the more syllables are added and that it is not strongly related to language proficiency. The slightly better performance of the advanced group (although statistically not significant except for foot duration) seems to suggest that more experience with the language may have a positive effect on the acquisition of timing properties of the English rhythm. This is in line with the observation that L2 learners seem to adjust their L1 motor plans in acquiring L2 phonology (Flege, Takagi & Mann, 1995Flege, J., Takagi, N., & Mann, V. (1995). Japanese adults can learn to produce English /ɻ/ and /l/. Language and Speech, 38, 25-55.
). However, it seems the advanced group in this study did not acquire English timing patterns adequately to block L1 transfer. This suggests that such prosodic aspects are difficult to master, and they need more efforts and time to acquire (cf. Abu Guba, 2021Abu Guba, M. N. (2021). Gemination within English loanwords in Ammani Arabic: An Optimality-theoretic analysis. Journal of Linguistics, 57(1), 1-38. http://dx.doi.org/10.1017/S0022226720000183 , and Abu Guba et al., 2023cAbu Guba, M. N., Mashaqba, B., Jarbou, S. & Al-Haj Eid, O. (2023c). Production of vowel reduction among Jordanian Arab learners of English: Acoustic investigation. Poznan Journal of Contemporary Linguistics. https://doi.org/10.1515/psicl-2022-2011.
, who reported that Jordanian-Arabic advanced speakers of English performed better than intermediate speakers producing English prosodic aspects but failed to perform in a near-native manner).

5. CONCLUSION

It has been shown that the English NSs tend to employ PS more than do the two groups of NNSs. However, these results show that isochronous foot duration and polysyllabic shortening are a tendency in English speech timing, rather than a fundamental process. The performance of the advanced group was slightly better than that of the intermediate group, but the differences between the two NNS groups were not statistically significant except for the differences in foot duration. It seems that the NNSs still use the mechanisms of their L1 rhythm (which is less stress-timed than that of English (cf. Section 2). A future study that explores PS in native Jordanian colloquial Arabic words is recommended to find out the extent to which L1 transfer plays a role in acquiring this feature.

Findings suggest that acquiring the timing patterns of the stress-timed English rhythm is challenging to Arabic-speaking NNSs. It seems that the NNSs need to be made explicitly aware of these timing properties as a prerequisite to reduce the effect of L1 transfer and ultimately acquire these timing patterns. It is likely that explicit teaching and training on these aspects could be helpful here, which is left for future research. English language learners and teachers should pay more attention to timing patterns, which would help boost intelligibility and reduce foreign accentedness. They should work on mastering English durational variation quite early especially because Arabic is rhythmically different from English