Nowadays, English is the most extensively studied foreign language in the world. Since English has become the dominant international language, the number of motivated learners has increased steadily. Iranian people are no exception to this phenomenon. Many Iranians, especially students, learn English at a high level so that they may interact with foreigners all over the globe. Iran (also known as Persia) is located in Western Asia. It has a population of about 83 million (Gerland et al., 2019). The main and official language of the country is Persian (also called Farsi) but since Iran is a multicultural country comprising numerous ethnic and linguistic groups such as Persians, Turks, Gilaks, Kurds, Lors, Armenians, Arabs, Baluchis, Turkmen, Assyrians, and Georgians (among others), many other languages are spoken among these groups in distinct areas of the country as well, so that bilingualism and multilingualism are common phenomena.

 

 

Persian has six vowels, arranged in a 2 × 3 inventory with three degrees of height (high, mid, low) and two degrees of constriction place (front unrounded, back rounded). Azerbaijani has the same six peripheral vowels, in approximately the same positions, but the inventory is augmented with three central vowels /y, ɯ, œ/. The pure (monophthongal) vowel system of American English is more complex. Although considerable regional variation exists, most varieties distinguish eleven vowels that are normally analyzed as monophthongs, as illustrated in Figure 1/C. This system has five front vowels and five back vowels, with four degrees of height: high, high-mid, low-mid and low. Seven vowels are long, the remaining vowels are short. The short vowels are articulated rather more to the center of the vowel space, while the long vowels assume articulation places along the outer periphery, i.e., along the front and back edges of the vowel space. The centralized short vowels are also called lax, while the peripheral long vowels are called tense. Our analysis of the American English vowel system follows Celce-Murcia et al. (2010), Yavaş (2011). For details and motivation of choices we refer to Afshar and Van Heuven (2022) or to Afshar (2022).

 

 

The results show that the monolinguals and bilinguals have different pairings of the AE vowels to the vowels of Persian. Monolingual Persian speakers have SC contrasts for the AE long and short mid vowel pairs: /ɪ, e/ both assimilate to Persian /e/, while /ʊ, o/ are paired with Persian /o/. The bilinguals show a different pairing. For them, the high and mid-high AE vowels /i, ɪ/ and /u, ʊ/ project onto Persian /i/ and /u/, in spite of the difference in duration between the members of the pairs. When asked to assimilate the AE vowels to the vowel inventory of Azerbaijani, the bilinguals show the same assimilation pattern that was seen in their Persian mode, so that we may provisionally conclude that the perceptual representation of the Persian vowel system for the bilinguals is influenced by the vowels of their first language, i.e., Azerbaijani (which tallies with the results reported by Mirahadi et al., 2018). Interestingly, when responding in Azerbaijani mode, the AE back vowels /ʊ, o/ are both paired with the central rounded mid vowel /œ/, one of the vowels that is not shared between Persian and Azerbaijani. The details of the pairing suggest that AE /o/ is considered a better token of Azerbaijani /œ/ than AE /ʊ/ is, which places the AE /ʊ, o/ contrast a Category Goodness scenario (CG, marked in yellow highlight in Table 1), from which relatively mild learning problems are predicted. The pairing with /œ/ suggests that the bilinguals hear the centralized vowel quality of AE /ʊ/ and of the beginning of /o/. Finally, the low-back AE vowels /ɔ, ɑ/, both of which are pronounced long, project onto the same vowel in Persian as well as in Azerbaijani for both groups of EFL learners. Although this predicts a learning problem for the EFL learners, the general advice is not to make this a priority in the teaching of American English pronunciation. The /ɔ, ɑ/ contrast has a low functional load, and is subject to the low-back vowel merger in the pronunciation of most native speakers of American English, who then pronounce all low back vowels as low /ɑ/ (e.g., Ladefoged, Johnson, 2011: 212–213; Carley, Mees, 2020).