PrécisAdults discriminate many non-native consonant contrasts poorly, but exceptions offer key insights about listeners’ knowledge of their native phonological systems. The Perceptual Assimilation Model (PAM: Best, 1995) predicts monolinguals’ perception, but has not been extended to bilinguals. We tested PAM predictions for bilinguals vs. monolinguals, as compared to those for an adult extension of the Articulatory Organ (AOH) hypothesis (Goldstein & Fowler, 2003), which posits that infants find contrasts within a single articulatory organ less discriminable than contrasts between two different organs. Early bilingual (Ukrainian-Australian English) and monolingual (Australian-English) adults were examined for perception of between-organ versus within-organ non-native and native fricative contrasts. Results were consistent with PAM predictions, going beyond basic AOH predictions. Thus, bilingual vs. monolingual language experience affects adults’ non-native speech perception, requiring modifications of the AOH as it applies to adults.

ResultsDiscrimination: 3-way ANOVA on % correct responses

The Stimulus Language x Organ interaction was significant, F(1, 26) = 13.41, p = .001, p

2 = .340, which was qualified by a 3-way interaction with Language Background, F(1, 26)= 4.33, p = 0.05, p

2 = .14 (Figure 3).

Both groups discriminated ENG > NCN, and discriminated ENG within-organ [θ]-[f] better than between-organ [θ]-[s]. But the bilinguals alone discriminated NCN between-organ [χ]-[ħ] better than within-organ [χ]-[x].

Perception of native and non-native fricative contrasts by Ukrainian-Australian English bilinguals and Australian English monolinguals.

Tamara A. Kencalo+, Catherine T. Best+*, Michael D. Tyler+ & Louis M. Goldstein*‡

+MARCS Auditory Laboratories, University of Western Sydney, Australia*Haskins Laboratories, New Haven CT, U.S.A. ‡ Yale University, New Haven CT, U.S.A.

Figure 4. Total mean percentages of each Assimilation Type for NCN Pharyngeal-Uvular and Uvular-Velar contrasts, according to categorization and ratings by monolinguals and bilinguals.

Future researchFuture research should investigate the PAM and AOH hypotheses and include alternate non-native within and between-organ contrasts for ENG monolinguals and UKR-ENG bilinguals to investigate whether adult discrimination of within and between-organ consonant contrasts differs for other target consonants or languages and is not language specific.

Other types of bilinguals should also be tested, such as Arabic-English bilinguals for whom both the pharyngeal [ħa] and the uvular [χa] fricatives exist in their L1 to extend the present findings to additional L1 systems.

AcknowledgementsThis research was supported by NIH grant DC00403 (Principal Investigator: C. Best). Many thanks to Elizabeth Beach who assisted in the stimulus development of the English tokens. We are most grateful to all the participants who agreed to take part in this research, and to our Nuu Chah Nulth speaker and to colleagues Bryan Gick and Ian Wilson, who helped us record the NCN stimulus materials at the University of British Columbia.

BackgroundAdults have difficulty discriminating some, but not all, non-native consonant contrasts (Best et al., 1988, 2001).

The Perceptual Assimilation Model (PAM) (Best, 1995) posits that the ease or difficulty of a given non-native contrast depends on the perceived similarity of its consonants to those of the native phonology.

Articulatory Phonology (AP)Phonological elements in speech are defined by:

Articulatory organs of the vocal tract Constrictions made by the active articulators (see Figure 1):

• at specific constriction locations• using specific constriction degrees

Articulatory Organ Hypothesis (AOH)A recent AP proposal is that infants attend more to the articulatory organ that is active in a gesture than to the specific gestures a given organ makes. The AOH predicts infants will continue to discriminate between-organ contrasts but will show a decline for within-organ ones (Goldstein & Fowler, 2003).

Infant perceptual findings support the AOH (Best & McRoberts, 2003): • Within-organ contrast shows developmental decline by 10 months• Between-organ contrast shows no decline

We extended PAM and AOH to adults differing in language experience:Monolinguals vs. Bilinguals whose languages differ in the target contrasts

The Present StudyEarly proficient bilingual (Ukrainian [UKR] - Australian English [AusE]) and monolingual (AusE) adults completed perceptual tests on two non-native voiceless fricative contrasts from Nuu Chah Nulth (NCN), a native Canadian language, and two native (L1) or early second language (L2) English (ENG) voiceless fricative contrasts. One contrast from each language was a between-organ distinction, the second a within-organ distinction (see Figure 2):

NCN: [χa]-[ħa] tongue body vs. root uvular vs. pharyngeal[χa]-[xa] tongue body uvular vs. velar

ENG: [θa]-[fa] lips vs. tongue tip interdental vs. labiodental[θa]-[sa] tongue tip interdental vs. alveolar

ENG has no posterior (guttural) fricatives except voiceless [h] (larynx: glottal).Ukrainian (UKR) has [xa] (tongue body: velar) and voiced [ɦ] (larynx: glottal).

PredictionsAOH predicts that within-organ contrasts are less discriminable than between-organ contrasts even for adults, and regardless of language experience

PAM predicts that: Monolinguals should assimilate all NCN fricatives to the only ENG

guttural fricative, [h]. If two NCN consonants differ in perceived goodness of fit to [h] (CG assimilation), discrimination will be good; if no goodness difference is perceived (SC assimilation) discrimination will be poor.

Bilinguals should assimilate NCN [χ] and [x] to UKR [x] (SC assimilation) and discriminate it poorly. They may assimilate NCN pharyngeal [ħ] to UKR [ɦ] or ENG [h] (glottal), showing TC assimilation of [χ]-[ħ] and excellent discrimination; or they may assimilate [ħa] to UKR [x], with CG or SC assimilation and less-good to poor discrimination of [χ]-[ħ].

MethodParticipants

Monolinguals: Australian-English (AusE) n =16 (10 female, Mage = 22.69, range = 18-35 years)

Bilinguals: Ukrainian (UKR)-AusE n = 12 (7 female, Mage = 33.42, range = 20-49 years)

Stimulus Materials 4 tokens each:

• 3 target ENG /Ca/ syllables by native female AusE speaker)• 3 target NCN /Ca/ syllables by native female NCN speaker)

Tokens were selected for best match on duration, amplitude and frequency characteristics, based on acoustic analyses (Praat).

Categorisation: 2 on group differences in assimilation types

Categorization of each NCN consonant determined per participant : Categorised: > 50% of labels as the same native consonant Uncategorized: <50% of labels in any single native category

Assimilation types determined for each NCN contrast per participant: SC = Categorized to same native consonant, ns diff. in ratings CG = Categorized to same native consonant, significant rating diff. TC = Categorized to two different native consonants UC = One NCN consonant Categorized, the other Uncategorized

Monolinguals categorised all NCN consonants to ENG [h]. Bilinguals used mostly UKR responses, especially [x] for NCN [x] and [χ]. Bilinguals assimilated NCN between-organ [χ]-[ħ] as TC significantly more often than monolinguals did, 2

(3, 28) = 12.79, p < .005. Both groups assimilated the NCN within-organ [χ]-[x] contrast primarily as SC (see Figure 4)

Discussion and ConclusionsLanguage experience played a crucial role in perception of the NCN contrasts, according to the significant Stimulus Language x Organ x Language Background interaction and the group differences in assimilation of the between-organ NCN contrast. This suggests that perception of the two non-native contrasts was strongly affected by L1 exposure, ENG for the monolingual group and UKR for the bilinguals. The groups’ NCN assimilation patterns and discrimination levels strongly support PAM predictions, more than they support the basic AOH predictions originally developed for infants.

Specifially, bilinguals displayed SC assimilation of the within-organ NCN contrast (tongue body: [χ]-[x]) to their UKR velar [x]. They also showed poorer discrimination of this contrast than of the between-organ NCN contrast (tongue body vs. root: [χ]-[ħ]), which the majority assimilated as TC. By comparison, monolingual ENG listeners assimilated all NCN fricatives to [h], displaying predominantly SC assimilation of both NCN contrasts. They showed equivalent discrimination of the [χ]-[x] and [χ]-[ħ] contrasts, consistent with PAM predictions, but failing to support a simple AOH between > within organ advantage for these contrasts. A possibility worth considering in future is that for adult speakers of a language like ENG, which does not make contrastive use of tongue body versus root, these are not treated as separate organs (single organ = tongue dorsum).

Interestingly, the majority of bilinguals categorised the non-native fricatives to their L1 (UKR), even though all have spent the majority of their lives in Sydney, an English dominant city, all are English-dominant themselves, and all were participating in a study conducted entirely in ENG. Comparing the present findings in a single-language dominant city to studies in bilingual cities such as Barcelona (Pallier et al., 1997; Bosch et al., 2000; Navarra et al, 2005), it is clear that in both situations, early proficient bilinguals are likely to assimilate non-native consonants to their L1, perhaps especially when it is advantageous for non-native perception.

ProcedureDiscrimination

AXB procedureseparate tests for each language (order counterbalanced)separate subtests per contrast within language (counterbalanced)8 blocks of 16 trials per subtesttokens presented equally in AAB, ABB, BBA, BAA trials per subtest8 practice trialsInterstimulus interval (ISI) = 1 s; ITI (trials) = 3.5 s; IBI (blocks) = 5

s

CategorisationRandomized presentation of individual tokensSeparate tests for each language (order counterbalanced)Participants wrote what each consonant sounded like to them

•Monolinguals: ENG orthography•Bilinguals: UKR or ENG orthography

They then gave a goodness-of-fit rating (1= very poor, 7 = excellent)

Figure 3. Mean percent correct discrimination, Stimulus Language x Organ x Language Background interaction. Error bars represent standard errors of the mean.

Monolingual

50

70

90

NCN ENG

Stimulus Language

Mean % Correct

Between

Within

Bilingual

5060708090

100

NCN ENG

Stimulus Language

Mean % correct

Between

Within

Pharyngeal-Uvular contrast

0

25

50

75

100

SC TC CG UC

Assimilation Types

total percentages

MonolingualBilingual

Uvular-Velar contrast

0

25

50

75

100

SC TC CG UC

Assimilation Types

total percentages

MonolingualBilingual

Figure 1. Schematic representation of the active articulators and their geometrical organisation in the vocal tract, according to AP theory.

Figure 2. Schematic representation of the within-organ versus between-organ contrasts in native English fricatives (left) and non-native NCN fricatives (right), according to the AOH Hypothesis.

PAM Predictions Two Category (TC) – When two non-native consonants are

assimilated to two native categories, discrimination is excellent. Single Category (SC) – When two non-native consonants are

assimilated to one native category equally, discrimination is poor. Category Goodness (CG) – When two non-native consonants are

assimilated to the same native category but with varying goodness of fit, discrimination is good to very good.

Uncategorised-Categorized (UC) – When one non-native consonant is unclearly categorized while the other is clearly assimilated to a native category, discrimination is good to excellent.

Assimilations depend on similarity of native and non-native articulatory gestures, per Articulatory Phonology (Browman & Goldstein, 1992).

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