Effects of Competence, Exposure, and Linguistic Backgrounds on Accurate Production & Perception of English Vowels by Nat

1. Effects of Competence, Exposure, and Linguistic Backgrounds on Accurate Production & Perception of English Pure Vowels by Native Japanese and Mandarin Speakers Malcolm A. Finney, James A. Till, and Naoko Tamura California State University, Long Beach

2. PURPOSE & RATIONALE • To investigate effects of linguistic backgrounds, degrees of English competence and exposure , and acoustic distance between L1 and L2 vowels on accurate production of 9 pure American English (AE) vowels by native speakers of Japanese (a 5 pure vowel system) and Mandarin (a 7 pure vowel system). Currently, there is incomplete understanding of the causes of this difficulty and specific vowels affected.

3. PURPOSE & RATIONALE • Target English Vowels: [i,,e,,,a,o,,u] • Beet, Bit, Bait, Bet, Bat, Bought, Boat, Pull, Pool. • Target vowels in Mandarin: [i,e,,a,o,u] • Target vowels in Japanese: [i,e,a,o,u]

4. Critical/Sensitive/Optimal Period for L2 Acquisition? • Early proposals stipulated native-like phonological acquisition was impossible or extremely unlikely after puberty because of age-related changes in the way the brain processed language, resulting in fossilization, a permanent inability to accurately produce and perceive sound distinctions made in L2 but not in L1.

5. Critical/Sensitive/Optimal Period for L2 Acquisition? • Some prefer ‘sensitive/optimal period’: Gradual decline in not abrupt end to ability; increasing difficulty not inability. Some post-puberty L2 learners (ranging from 5% to 25%) successfully acquire native-like pronunciation skills. This small “hypothetical exception” should not preclude biological rationale for a sensitive period. Sensitive period indicates a period of “heightened responsiveness” followed by periods of “lesser responsiveness. This affects both production and perception of new L2 phonemes

6. Problems with Critical/Sensitive/Optimal Period • Nature of the transfer or substitution process? To what extent is it triggered by age-related neurological or biological changes to the way the learner approaches the task of L2 acquisition? Are some L2 properties more/less likely to be transferred or substituted? Is there symmetry or asymmetry between production and perception errors?

7. Other Possible Sources of Difficulty • Social/psychological changes & identification with L1 & L2 culture. Loss of motivation in developing accent-free speech. • Variability in degree of empathy, anxiety, inhibition, risk-taking, attitude, and motivation. • Effects of Exposure: Frequency Thresholds and Time Thresholds – make allowance for post-puberty learners to acquire native-like pronunciation.

8. Asymmetry between L2 Production & Perception Abilities? • To what extent are L2 phonological difficulties conditioned by a lack of motor control or triggered by an inaccurate perception of L2 sounds (i.e. production errors have a perceptual basis? • Is production more challenging than perception?

9. PURPOSE & RATIONALE • Effects of Linguistic Backgrounds: • Substitution patterns in production may reflect similar patterns for speakers from same linguistic backgrounds or may reflect universal processing strategies. • Speakers from same linguistic backgrounds may encounter perception difficulties with same sounds.

10. PURPOSE & RATIONALE • Effects of Competence & Exposure: Degree of competence and exposure may influence the degree of accuracy in production. Learners may produce and perceive new L2 vowel categories more accurately with increasing competence in and exposure to L2.

11. PURPOSE & RATIONALE • Effects of Acoustic Distance: Perception of differences between L1 & L2 vowels may be influenced by degree of perceived acoustic distance or space between L2 vowel & other L1 vowels. The greater the distance, the more likely the learner will consider the L2 vowel as ‘new’ possibly leading to establishment of new vowel category. The less the distance, the more likely the L2 vowel will be considered identical to existing L1 vowel possibly preventing establishment of a new L2 vowel category.

12. Effects of Acoustic Distance • L2 learners are more likely to assume that an existing L1 sound and a TL sound are identical if their positions of articulation are acoustically close. More interference errors for similar sounds both in producing & perceiving L2 sound. L2 sounds that are acoustically distant from existing L1 sounds will be perceived as new & unrelated to existing TL sounds. Learner will make conscious effort to produce ‘new’ sound thereby avoiding L1 substitutions. Hansen (2006): “the substituted sound is often the most acoustically or articulatorily similar sound to the target language sound.”

13. Pure Vowels

14. PARTICIPANTS& PROCEDURES • 11 AE speakers, 21 Japanese speakers, & 24 Mandarin speakers. All subjects completed: • 1) Language History questionnaire; 2) L2 Proficiency Assessment protocol 3) a set of production & Perception tasks. • Production errors were digitally analyzed using computer software that identifies pronunciation deviations from English norms & degree of deviation from such norms. That is – objective measurement not NS subjective judgments (used in a number of studies) was used.

15. PRODUCTION TASKS • A two-minute monologue • A one-minute reading aloud for comprehension (comprehension questions following) • “Carrier” phrases plus target sound in word. • Word & sentence production elicitation task. Producing words with target sounds in isolation (word repetition task) and in “Carrier phrases (sentence repetition task) • Assessment focused on the accurate production of nine pure English vowels (/i,,e,,,a,o,,u/)

16. PRELIMINARY RESULTSF1 & F2 MEASURES FOR WORDS • SUBJECTS: Results are presented for 30 young adults: 5 female and 5 male subjects for each native language group. L2 exposure, tested competence, and use varied.

17. METHODS – Word Elicitation & Recording Five productions of each stimulus words were elicited in randomized order and digitized (16 bit, 22 kHz) using a custom designed computer program operating on a low noise computer in a quiet room. Participants wore a head mounted microphone.

18. The Vowels Beet Bit Bait Bet Bat Bought Boat Book Boot

19. METHODS - MEASUREMENT Mean F1 & F2 frequencies were extracted from the vowelmidpoint using the Praat program (Boersma, P. & Weenink, 2006)

20. F1 & F2 MEASUREMENT Reliability Probe – JM17 /ae/

21. VOWEL AREAS - MALE

22. VOWEL AREAS – FEMALE

23. LAX VOWELS – MALE

24. LAX VOWELS – FEMALE

25. HIGH INTRA-SUBJECT F2 VARIABILITYRepeated Trials of same Vowel by subject with 4.5 years of L2 use.

26. Conclusions for Production Task • There was substantial variability in L2 vowel production accuracy between subjects in both the Japanese(JS) and Mandarin(MS) speaking group. • Some subjects showed substantial variability on repeated trials for the same L2 vowel. • Examination of individual patterns rather than group means may be necessary.

27. Conclusions for Production Task • Despite the variability, limited group trends were identified: • Both the JS and MS groups tended to produce lax L2 vowels more like the tense L2 vowel counterpart. F2 was increased (tongue fronting) and F1 was lowered (tongue raising). • Both the JS and MS groups tended to produce [o] and [a] with a reduced F2 and an increased F1. This suggests a tongue position that was backed and lowered relative to the English speakers.

28. Perception Tasks Word Identification Task • Subjects were presented with 5 productions of 9 words containing 9 target English vowels via oral computer recording (by NS of AE), randomized by a computer program. Participants were instructed to identify the target word from a list of choices provided (the nine target words). The more choices there are, the less likely it is to provide choices that may not accurately reflect the learners’ choice of substitution. • Target Words: Beat [i]; Bit []; Bait [e]; Bet []; Bat[]; Bought[a]; Boat[o]; Pull[]; Pool[u]

29. Results of Identification TaskEffects of Linguistic Background • Effects of linguistic backgrounds for 8 of 9 vowels (tables 2, 3, &4). • Mandarin speakers were highly significantly less accurate in identifying the front vowels [e,,,,i] compared to the English & Japanese subjects • Japanese speakers were significantly or marginally significantly less accurate in identifying the back vowels [a,o] (selecting ‘boat’ for ‘bought’ or vice versa) compared to English & Mandarin subjects. • Though both Japanese & Mandarin speakers in general were less accurate than the native English speakers, results indicate differential degrees of accuracy on the basis of linguistic backgrounds.

30. Effects of Acoustic Distance • Partial confirmation of effects. Japanese & Mandarin subjects were highly significantly less accurate in perceiving [] compared to English subjects • Mandarin subjects additionally were highly significantly less accurate in perceiving [i] compared to English subjects. • There were no significant mean effects in perceiving [] in spite of its acoustic proximity to [u] & absence in Japanese & Mandarin. • Mandarin subjects were highly significantly less accurate in perceiving [u] compared to Japanese & English subjects.

31. Effects of Acoustic Distance [,] • Mandarin subjects experienced difficulty & were significantly less accurate in perceiving difference between [] (absent in Mandarin) and [] (present in Mandarin) compared to English & Japanese subjects since both vowels are acoustically close. • There was no significant difference in identification of both vowels between Japanese & English subjects. In spite of absence of [] in L1, Japanese speakers perceived it as new & distinct sound because its acoustic distance from other Japanese vowels.

32. [a,o] • Japanese but not Mandarin subjects were significantly less accurate in perceiving difference between [a] and [o] compared to other groups in spite of presence of both vowels in Japanese and Mandarin & acoustic distance between both vowels. • Proposal that the more similar the L2 sound is to an existing but different L1 sound the stronger the likelihood of L1 interference and persistent difficulty in perceiving that L2 sound was only partially borne out.

33. Effects of English CompetenceTables 5 – 9 • J-Low & M-Low subjects were least accurate compared to English & Medium & High competence subjects. • Differences were significant primarily for Low subjects vs. High & English subjects. • Differences among Medium, High & English subjects for the most part were not significant. • Significant effects of linguistic backgrounds were evident only during the early stages of L2 development.

34. Effects of English Exposure(Tables 10 & 11) • Significant differences on basis of average lengths of residence in country in which English is used as native & primary language. Subjects with short lengths of residence were significantly less accurate than English subjects. • Only exception for Japanese subjects was for [u] for which participants with medium lengths of residence were significantly the least accurate. • Difficulty may be temporary & may disappear with increasing residency in L2 country. • Statistical analysis of effects of active English use in English-speaking country indicated a similar trend.

35. Word Discrimination (Word Differentiation) Task • Beet/Bit; Bit/Bait; Bait/Bet; Bet/Bat; Bat/Bought; Bought/Boat; Pull/Pool • See Table 12

36. Word Discrimination (Word Differentiation) Task • Participants listened to sequence of 3 stimuli containing 2 of the target vowels presented sequentially with a 700 ms inter-stimulus interval: 2 identical and 1 different. Vowel in the different word was adjacent to vowel in other 2 words in sequence in terms of vowel height or frontness/backness. Sequential position of the odd stimulus word was randomly determined by the computer program. • After listening to sequence, participants were required to identify which stimulus was different from the other two. A choice was forced by the computer program before the next sequence was orally presented. Participants had the option to listen a second time before responding.

37. Discrimination Task: Linguistic Backgrounds (Tables 13 & 14) • Accuracy was high across linguistic backgrounds. No significant differences by Post Hoc tests. • Japanese subjects recorded lowest means/% for back vowel sequences [u] & [uu]. • Mandarin subjects recorded lowest means/% for front vowel sequences [] & []. • Pairwise Comparisons (less rigid) indicated significant differences for sequence []

38. Discrimination/Differentiation TaskCompetence Levels (Tables 15 & 16) • No significant differences by Post Hoc tests. Pairwise comparisons indicated statistically significant (or marginally significant) differences between Low & English subjects

39. Discrimination/Differentiation TaskEnglish Exposure (Tables 17 & 18) • Some significant differences between lengths of residency in native English-speaking country and accurate discrimination for Japanese but not Mandarin subjects. • Similar results for effects of active English use.

40. Implications • General effects of linguistic backgrounds on perception difficulty but primarily for learners with low L2 competence & exposure. • Acoustic proximity between L1 & L2 vowels may be a source (but not the only source) for widespread difficulty. • Production difficulty is likely to be persistent in spite of increasing L2 competence & exposure.