Why non-native speakers of English talk the way they do? Several linguists like Gass & Selinker, Major and Lado have investigated on this issue and agreed at least upon one principle - the Contrastive Analysis Hypothesis (CAH). It states that two languages have to be compared in order to determine possible errors since the mother tongue plays one important role when it comes to second language acquisition. That is, L1 interference. The following essay should give an approximate explanation on this issue by examining Russian and Spanish speakers acquiring English. The focus will lie on phonology, especially on obstruents and their distribution. According to CAH, it is necessary to analyze Russian, English, and Spanish at first, before looking at the different errors in pronunciation at the basis of Data Set 1.
According to Data Set 1, Russian exhibits a voicing contrast between the following obstruents in word-initial position: [p] and [b], e. g. 2. пар [par] ‘steam’ and 1. бар [bar] ‘bar’; [t] and [d], e. g. 12. том [tom] ‘tome’ and 11. дом [dom] ‘house’; [k] and [g], e. g. 21. кора [kara] ‘bark’ and 22. гора [gara] ‘mountain’; [s] and [z], e. g. 27. сова [sava] ‘owl’ and 42. зов [zof] ‘call’; [f] and [v], e. g. 36. фара [fara] ‘headlight’ and 37. варить [varjitj] ‘to boil’; [ʃ] and [ʒ], e. g. 43. шорох [ʃorɘx] ‘rustle’ and 42. жор [ʒor] ‘big appetite’. The same voicing contrast of the mentioned obstruents occurs also intervocalically: for instance in 10. драпа [drapa] ‘thick woolen cloth (gen)’ and 8. рабы [rabɯ] ‘slaves’; 18. ротик [rotjik] ‘little mouth’ and 20. годик [godjik] ‘year (dim)’; 26. рука [ruka] ‘hand’ and 24. круги [krugji] ‘circles’; 31. кваса [kvasɘ] ‘bread drink (gen)’ and 29. грузить [gruzjitj] ‘load up’; 35. графа [grafa] ‘Earl (gen)’ and 33. зова [zova] ‘call (gen)’; 39. крыыша [krɯʃa] ‘roof’ and дрожать [draʒatj] ‘to shiver’. However, this voicing contrast does not occur in word-final position which becomes evident when looking at the different environments of a letter in a word as the following examples show: like in 6. раб [rap] ‘slave’, 15. род [rot] ‘gender’, 23. круг [kruk] ‘circle’, 28. груз [grus] ‘load’, 32. зов [zof] ‘call’ and 40. дрожь [droʃ] ‘shiver’.
As far as English is concerned, it exhibits a voicing contrast in word-initial, intervocalic and word-final position as the following examples show: bag [bæg], abode [əbod] and knob [nɑb] vs. pig [pɪg], supper [sʌpə] and hope [hop]; dish [dɪʃ], hoody [hʊdi] and bad [bæd] vs. teach [titʃ], wetter [wɛtə] and heat [hit]; cool [kul], maker [mekə] and pack [pæk] vs. good [gʊd], tiger [taygə] and nag [næg]; see [si], messy [mɛsi] and nice [nays] vs. zoo [zu], lazy [lezi] and rose [roz]; for [fɔr], beefy [bifi] and leaf [lif] vs. vote [vot], ever [ɛvɘ] and have [hæv]; this [ðɪs], whether [wɛðɘ] and booth [buð] vs. thanks [θæŋks], ethos [iθɑs] and with [wɪθ]; sure [ʃʊr], pushy [pʊʃi] and wish [wɪʃ] vs. jet [ʒɛt], measure [mɛʒɘ] and garage [gɘrɑʒ]. By comparing both languages, one would assume that errors might occur in word-final position. This assumption is going to be proved in the following part.
In fact, the analysis of the errors made by Subject 1 shows that consonants tend to be voiceless in word-final position as in 1. [bæk], 3. [nɑp], 12. [fʌtʃ], 19. [petʃ], 22. [fit] and 26. [ros] which can be explained due to the fact that Russian consonants become voiceless in word-final position. What is striking is the fact that in 15. [fʌtʃi] the affricate becomes voiceless, too, although Russian exhibits a voicing contrast intervocalically. Nevertheless, as Data Set 1 shows the voiced affricate [dʒ] does not exist in Russian which is a type of underdifferentiation according to Major (2001, 31). Therefore, the closest accordance must be found which is in this case the voiceless phoneme.
According to Data Set 1, Spanish exhibits a voicing contrast of the following obstruents in word-initial position: [p] and [b], e. g. 3. pesa [pesa] ‘weight (dep)’ and 1. beso [beso] ‘kiss’; [t] and [d], e. g. 16. toga [toγa] ‘toga’ and 23. donde [donde] ‘where’; [k] and [g], e. g. 6. cava [kaβa] ‘wine cellar’ and 13. gota [gota] ‘drop’. These are therefore different phonemes. In addition to that, they also have allophones which occur intervocalically as the following examples show: like [β] in 5. loba [loβa] ‘wolf (f.)’, [γ] in 21. fuego [fueγo] ‘fire’ and [γ] in 25. lado [laðo] ‘side’. Moreover, the phoneme [s] occurs in word-initial position but is realized as the allophone [z] before voiced consonants like in 17. saga [saγa] ‘saga’ and 35. mismo [mizmo] ‘same, self’. It cannot be considered that Spanish does exhibit a voicing contrast in word-final position since only vocals, [s], [r], [l] and [ð] occur, according to Data Set 1. Based on this analysis of Spanish phonology, it can be considered that the examined obstruents [β] and [γ] are absent in English, by contrast, the English obstruents [v], [ʃ], [ʒ] and [θ] are absent in Spanish. Whether these obstruents lead to errors will be examined in the next part.
 However, all these obstruents occur in other varieties of Spanish, especially [θ] which belongs to the standard.