The acquisition of second language (L2) prosody is of crucial importance for intelligibility and perceptions of foreign accentedness (Flege, Munro, & MacKay, 1995; Tajima, Port, & Dalby, 1997; White & Mattys, 2007). 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, 1972). This contributes to the perception of a stress-timed rhythm where interstress intervals tend to be regular (Lehiste, 1977; Kim & Cole, 2005; see Turk, 2012, 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, 2023b) 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, 2014; Turk & Shattuck-Hufnagel, 2013). 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, 2013). 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, 2021; Abu Guba, Daoud & Jarbou, 2023). 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, 2011). 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, 2014). 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.

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, 1972; Port, 1981; White & Turk, 2010). It was also found that PS was more evident in pitch-accented vowels than unaccented ones (e.g., Kim & Cole, 2005; White & Turk, 2010). 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, 1972; Port, 1981).

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, 1990; Turk & White, 1999; Turk & Shattuck-Hufnagel, 2000; White & Turk, 2010). 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, 2000).

Accentual lengthening, where segments receiving a pitch-accent/phrasal stress undergo lengthening (White & Turk, 2010), is greater in a monosyllable than in a disyllable, as in ‘knee’ and ‘kneecap’ (Turk & White, 1999). Furthermore, Turk and Shattuck-Hufnagel (2000) reported that PS was greater in pitch-accented words, an indication that accentual lengthening and PS are interrelated. White and Turk (2010) 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, 2007).

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) 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) 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, 2014).

In another study tackling PS among bilingual children, Gibson & Bernales (2019) 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).

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) 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, 2023a). 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?

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.

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