Acoustic variability within and across German, French, and American English vowels: phonetic context effects

English Speakers' Perception of Non-native Vowel Contrasts in Adverse Listening Conditions: A Discrimination Study on the German Front Rounded Vowels /y/ and /ø/

Previous research has shown that it is difficult for English speakers to distinguish the front rounded vowels /y/ and /ø/ from the back rounded vowels /u/ and /o/. In this study, we examine the effect of noise on this perceptual difficulty. In an Oddity Discrimination Task, English speakers without any knowledge of German were asked to discriminate between German-sounding pseudowords varying in the vowel both in quiet and in white noise at two signal-to-noise ratios (8 and 0 dB). In test trials, vowels of the same height were contrasted with each other, whereas a contrast with /a/ served as a control trial. Results revealed that a contrast with /a/ remained stable in every listening condition for both high and mid vowels. When contrasting vowels of the same height, however, there was a perceptual shift along the F2 dimension as the noise level increased. Although the /ø/-/o/ and particularly /y/-/u/ contrasts were the most difficult in quiet, accuracy on /i/-/y/ and /e/-/ø/ trials decreased immensely when the speech signal was masked. The German control group showed the same pattern, albeit less severe than the non-native group, suggesting that even in low-level tasks with pseudowords, there is a native advantage in speech perception in noise.

Spectral and Temporal Characteristics of Vowels in Konkani

The present study was undertaken to study the acoustic characteristics of vowels using spectrographic analysis in Mangalorean Catholic Konkani dialect of Konkani spoken in Mangalore, Karnataka, India. Recordings were done using CVC words in 11 males and 19 females between the age range of 18-55 years. The CVC words consisted of combinations of vowels such as (/i, i:, e, ɵ, ə, u, o, ɐ, ӓ, ɔ/) and consonants such as (/m, k, w, s, ʅ, h, l, r, p, ʤ, g, n, Ɵ, ṭ, ḷ, b, dh/). Recordings were done in a sound-treated room using PRAAT software and spectrographic analysis was done and spectral and temporal characteristics such as fundamental frequency (F0), formants (F1, F2, F3) and vowel duration. The results showed that higher fundamental frequency values were observed for short, high and back vowels. Higher F1 values were noted for open vowels and F2 was higher for front vowels. Long vowels had longer duration compared to short vowels and females had longer vowel duration compared to males. The acoustic information in terms of spectral and temporal cues helps in better understanding the production and perception of languages and dialects.

Individual variability and the effect of personality on non-native speech shadowing

The present study examines whether personality traits are predictive of success in non-native speech shadowing. Seventy-four monolingual native speakers of English shadowed French words containing high rounded vowels /y/ and /u/ produced by a native French model talker and provided information about their personality through a Big Five Inventory questionnaire. Acoustic analyses support the idea that some personality traits predicted the degree of similarity between the talkers and the model. In this case, shadowed productions by talkers who had higher scores in extraversion and neuroticism were significantly more similar to the model than those who had lower scores.

Online Assessment of Speech Perception and Auditory Spectrotemporal Processing in Spanish-English Bilinguals

PURPOSE

There is limited access to audiology services for the growing population of Spanish-English bilinguals in the United States. Online auditory testing can potentially provide a cost-effective alternative to in-person visits. However, even for bilinguals with high English proficiency, age of English acquisition may affect speech perception accuracy. This study used a comprehensive test battery to assess speech perception and spectrotemporal processing abilities in Spanish-English bilinguals and to evaluate susceptibility of different tests to effects of native language.

METHOD

The online battery comprised three tests of speech in quiet (vowel and consonant identification and words in sentences), four tests of speech perception in noise (two for intelligibility and two for comprehension), and three tests of spectrotemporal processing (two tests of stochastically modulated pattern discrimination and one test of spectral resolution). Participants were 28 adult Spanish-English bilinguals whose English acquisition began either early (≤ 6 years old) or late (≥ 7 years old) and 18 English monolingual speakers.

RESULTS

Significant differences were found in six of the 10 tests. The differences were most pronounced for vowel perception in quiet, speech-in-noise test, and two tests of speech comprehension in noise. Late bilinguals consistently scored lower than native English speakers or early bilinguals. In contrast, no differences between groups were observed for digits-in-noise or three tests of spectrotemporal processing abilities.

CONCLUSION

The findings suggest initial feasibility of online assessment in this population and can inform selection of tests for auditory assessment of Spanish-English bilinguals.

Articulatory Gain Predicts Motor Cortex and Subthalamic Nucleus Activity During Speech

Speaking precisely is important for effective verbal communication, and articulatory gain is one component of speech motor control that contributes to achieving this goal. Given that the basal ganglia have been proposed to regulate the speed and size of limb movement, that is, movement gain, we explored the basal ganglia contribution to articulatory gain, through local field potentials (LFP) recorded simultaneously from the subthalamic nucleus (STN), precentral gyrus, and postcentral gyrus. During STN deep brain stimulation implantation for Parkinson's disease, participants read aloud consonant-vowel-consonant syllables. Articulatory gain was indirectly assessed using the F2 Ratio, an acoustic measurement of the second formant frequency of/i/vowels divided by/u/vowels. Mixed effects models demonstrated that the F2 Ratio correlated with alpha and theta activity in the precentral gyrus and STN. No correlations were observed for the postcentral gyrus. Functional connectivity analysis revealed that higher phase locking values for beta activity between the STN and precentral gyrus were correlated with lower F2 Ratios, suggesting that higher beta synchrony impairs articulatory precision. Effects were not related to disease severity. These data suggest that articulatory gain is encoded within the basal ganglia-cortical loop.

Lexical and Phonetic Influences on the Phonolexical Encoding of Difficult Second-Language Contrasts: Insights From Nonword Rejection

Establishing phonologically robust lexical representations in a second language (L2) is challenging, and even more so for words containing phones in phonological contrasts that are not part of the native language. This study presents a series of additional analyses of lexical decision data assessing the phonolexical encoding of English /ε/ and /æ/ by German learners of English (/æ/ does not exist in German) in order to examine the influence of lexical frequency, phonological neighborhood density and the acoustics of the particular vowels on learners’ ability to reject nonwords differing from real words in the confusable L2 phones only (e.g., *l[æ]mon, *dr[ε]gon). Results showed that both the lexical properties of the target items and the acoustics of the critical vowels affected nonword rejection, albeit differently for items with /æ/ → [ε] and /ε/ → [æ] mispronunciations: For the former, lower lexical frequencies and higher neighborhood densities led to more accurate performance. For the latter, it was only the acoustics of the vowel (i.e., how distinctly [æ]-like the mispronunciation was) that had a significant impact on learners’ accuracy. This suggests that the encoding of /ε/ and /æ/ may not only be asymmetric in that /ε/ is generally more robustly represented in the lexicon than /æ/, as previously reported, but also in the way in which this encoding takes place. Mainly, the encoding of /æ/ appears to be more dependent on the characteristics of the L2 vocabulary and on one’s experience with the L2 than that of its more dominant counterpart (/ε/).

Acoustic vowel analysis and speech intelligibility in young adult Hebrew speakers: Developmental dysarthria versus typical development

BACKGROUND

Developmental dysarthria is a motor speech impairment commonly characterized by varying levels of reduced speech intelligibility. The relationship between intelligibility deficits and acoustic vowel space among these individuals has long been noted in the literature, with evidence of vowel centralization (e.g., in English and Mandarin). However, the degree to which this centralization occurs and the intelligibility-acoustic relationship is maintained in different vowel systems has yet to be studied thoroughly. In comparison with American English, the Hebrew vowel system is significantly smaller, with a potentially smaller vowel space area, a factor that may impact upon the comparisons of the acoustic vowel space and its correlation with speech intelligibility. Data on vowel space and speech intelligibility are particularly limited for Hebrew speakers with motor speech disorders.

AIMS

To determine the nature and degree of vowel space centralization in Hebrew-speaking adolescents and young adults with dysarthria, in comparison with typically developing (TD) peers, and to correlate these findings with speech intelligibility scores.

METHODS & PROCEDURES

Adolescents and young adults with developmental dysarthria (secondary to cerebral palsy (CP) and other motor deficits, n = 17) and their TD peers (n = 17) were recorded producing Hebrew corner vowels within single words. For intelligibility assessments, naïve listeners transcribed those words produced by speakers with CP, and intelligibility scores were calculated.

OUTCOMES & RESULTS

Acoustic analysis of vowel formants (F1, F2) revealed a centralization of vowel space among speakers with CP for all acoustic metrics of vowel formants, and mainly for the formant centralization ratio (FCR), in comparison with TD peers. Intelligibility scores were correlated strongly with the FCR metric for speakers with CP.

CONCLUSIONS & IMPLICATIONS

The main results, vowel space centralization for speakers with CP in comparison with TD peers, echo previous cross-linguistic results. The correlation of acoustic results with speech intelligibility carries clinical implications. Taken together, the results contribute to better characterization of the speech production deficit in Hebrew speakers with motor speech disorders. Furthermore, they may guide clinical decision-making and intervention planning to improve speech intelligibility. What this paper adds What is already known on the subject Speech production and intelligibility deficits among individuals with developmental dysarthria (e.g., secondary to CP) are well documented. These deficits have also been correlated with centralization of the acoustic vowel space, although primarily in English speakers. Little is known about the acoustic characteristics of vowels in Hebrew speakers with motor speech disorders, and whether correlations with speech intelligibility are maintained. What this paper adds to existing knowledge This study is the first to describe the acoustic characteristics of vowel space in Hebrew-speaking adolescents and young adults with developmental dysarthria. The results demonstrate a centralization of the acoustic vowel space in comparison with TD peers for all measures, as found in other languages. Correlation between acoustic measures and speech intelligibility scores were also documented. We discuss these results within the context of cross-linguistic comparisons. What are the potential or actual clinical implications of this work? The results confirm the use of objective acoustic measures in the assessment of individuals with motor speech disorders, providing such data for Hebrew-speaking adolescents and young adults. These measures can be used to determine the nature and severity of the speech deficit across languages, may guide intervention planning, as well as measure the effectiveness of intelligibility-based treatment programmes.

The Use of Vowel Length in Making Voicing Judgments by Native Listeners of English and Spanish: Implications for Rate Normalization

Among other characteristics, voiced and voiceless consonants differ in voice onset time (VOT; Lisker & Abramson, 1964). In addition, in English, voiced consonants are typically followed by longer vowels than their unvoiced counterparts (Allen & Miller, 1999). In Spanish, this relationship is less systematic (Zimmerman & Sapon, 1958). In two experiments, we investigated perceptual sensitivities of English and Spanish native speakers to following vowel length (VL) in categorizing syllables that ranged from a prevoiced bilabial stop [ba] to a long-lag bilabial stop [pa]. According to our results, English speakers show sensitivity to following vowels with VLs falling within an English-typical range (Experiment 1), but not when vowels are shorter and in a Spanish-typical range (Experiment 2). Interestingly, Spanish native speakers do not show sensitivity to following VL in either condition. These results suggest that VOT-VL tradeoffs in perception reflect phonological sensitivities of listeners and are not reducible to speech rate compensation.

Vowel Acoustics and Speech Intelligibility in Young Adults With Down Syndrome

Purpose Speech production deficits and reduced intelligibility are frequently noted in individuals with Down syndrome (DS) and are attributed to a combination of several factors. This study reports acoustic data on vowel production in young adults with DS and relates these findings to perceptual analysis of speech intelligibility. Method Participants were eight young adults with DS as well as eight age- and gender-matched typically developing (TD) controls. Several different acoustic measures of vowel centralization and variability were applied to tokens of corner vowels (/ɑ/, /æ/, /i/, /u/) produced in common English words. Intelligibility was assessed for single-word productions of speakers with DS, by means of transcriptions from 14 adult listeners. Results Group differentiation was found for some, but not all, of the acoustic measures. Low vowels were more acoustically centralized and variable in speakers with DS than TD controls. Acoustic findings were associated with overall intelligibility scores. Vowel formant dispersion was the most sensitive measure in distinguishing DS and TD formant data. Conclusion Corner vowels are differentially affected in speakers with DS. The acoustic characterization of vowel production and its association with speech intelligibility scores within the DS group support the conclusion of motor control deficits in the overall speech impairment. Implications are discussed for effective treatment planning.

Perception of American-English Vowels by Early and Late Spanish-English Bilinguals

Increasing numbers of Hispanic immigrants are entering the US and learning American-English (AE) as a second language (L2). Previous studies investigating the relationship between AE and Spanish vowels have revealed an advantage for early L2 learners for their accuracy of L2 vowel perception. Replicating and extending such previous research, this study examined the patterns with which early and late Spanish-English bilingual adults assimilated naturally-produced AE vowels to their native vowel inventory and the accuracy with which they discriminated the vowels. Twelve early Spanish-English bilingual, 12 late Spanish-English bilingual, and 10 monolingual listeners performed perceptual-assimilation and categorical-discrimination tasks involving AE /i,ɪ,ɛ,ʌ,æ,ɑ,o/. Early bilinguals demonstrated similar assimilation patterns to late bilinguals. Late bilinguals' discrimination was less accurate than early bilinguals' and AE monolinguals'. Certain contrasts, such as /æ-ɑ/, /ʌ-ɑ/, and /ʌ-æ/, were particularly difficult to discriminate for both bilingual groups. Consistent with previous research, findings suggest that early L2 learning heightens Spanish-English bilinguals' ability to perceive cross-language phonetic differences. However, even early bilinguals' native-vowel system continues to influence their L2 perception.

Big data suggest strong constraints of linguistic similarity on adult language learning

When adults learn new languages, their speech often remains noticeably non-native even after years of exposure. These non-native variants ('accents') can have far-reaching socio-economic consequences for learners. Many factors have been found to contribute to a learners' proficiency in the new language. Here we examine a factor that is outside of the control of the learner, linguistic similarities between the learner's native language (L1) and the new language (Ln). We analyze the (open access) speaking proficiencies of about 50,000 Ln learners of Dutch with 62 diverse L1s. We find that a learner's L1 accounts for 9-22% of the variance in Ln speaking proficiency. This corresponds to 28-69% of the variance explained by a model with controls for other factors known to affect language learning, such as education, age of acquisition and length of exposure. We also find that almost 80% of the effect of L1 can be explained by combining measures of phonological, morphological, and lexical similarity between the L1 and the Ln. These results highlight the constraints that a learner's native language imposes on language learning, and inform theories of L1-to-Ln transfer during Ln learning and use. As predicted by some proposals, we also find that L1-Ln phonological similarity is better captured when subcategorical properties (phonological features) are considered in the calculation of phonological similarities.

Vowel Formants in Normal and Loud Speech

Purpose This study evaluated how 1st and 2nd vowel formant frequencies (F1, F2) differ between normal and loud speech in multiple speaking tasks to assess claims that loudness leads to exaggerated vowel articulation. Method Eleven healthy German-speaking women produced normal and loud speech in 3 tasks that varied in the degree of spontaneity: reading sentences that contained isolated /i: a: u:/, responding to questions that included target words with controlled consonantal contexts but varying vowel qualities, and a recipe recall task. Loudness variation was elicited naturalistically by changing interlocutor distance. First and 2nd formant frequencies and average sound pressure level were obtained from the stressed vowels in the target words, and vowel space area was calculated from /i: a: u:/. Results Comparisons across many vowels indicated that high, tense vowels showed limited formant variation as a function of loudness. Analysis of /i: a: u:/ across speech tasks revealed vowel space reduction in the recipe retell task compared to the other 2. Loudness changes for F1 were consistent in direction but variable in extent, with few significant results for high tense vowels. Results for F2 were quite varied and frequently not significant. Speakers differed in how loudness and task affected formant values. Finally, correlations between sound pressure level and F1 were generally positive but varied in magnitude across vowels, with the high tense vowels showing very flat slopes. Discussion These data indicate that naturalistically elicited loud speech in typical speakers does not always lead to changes in vowel formant frequencies and call into question the notion that increasing loudness is necessarily an automatic method of expanding the vowel space. Supplemental Material https://doi.org/10.23641/asha.8061740.

Effects of Exposure and Vowel Space Distribution on Phonetic Drift: Evidence from American English Learners of French

Recent work by Chang has shown that even at the very earliest stages of second language (L2) acquisition, the phonetic implementation of speakers' native English phoneme categories is slightly modified by contact with L2 Korean, which is referred to as "phonetic drift." This study investigates whether rapid phonetic drift generalizes to another pairing of languages. We examined naïve American English learners of French, who were recorded producing both American English and French vowels after one and six weeks of a study abroad program in Paris. In addition, the Study Abroad group is compared with proficient American English L1 speakers of French who have been residents of Paris for at least five years, to investigate the impact of long-term use of an L2 on the vowel categories of L1. Whereas the Study Abroad group showed no evidence of phonetic drift after six weeks, the Paris Residents' American English vowel space shifted along F1 and several English vowels demonstrated clear movement toward French monolingual norms. A closer look at the high vowels provides insight into how phonetic categories are influenced both by drift and by a pressure to keep vowel categories distinct between the languages. The results are also discussed with respect to potential effects of the size of the vowel inventory and the amount of input required to cause phonetic drift.

Second Language Perception of Mandarin Vowels and Tones

This study examines the discrimination of Mandarin vowels and tones by native English speakers with varying amounts of Mandarin experience, aiming to investigate the relative difficulty of these two types of sounds for English speakers at different learning stages, and the source of their difficulty. Seventeen advanced learners of Mandarin (Ex group), eighteen beginning learners (InEx group), and eighteen English speakers naïve to Mandarin (Naïve group) participated in an AXB discrimination task. The stimuli were two Mandarin vowel contrasts, /li-ly/ and /lu-ly/, and two tonal contrasts, T1-T4 and T2-T3. The predicted difficulty for each contrast was hypothesized based on the assimilation of these sounds to English reported in previous work. The results showed that the Naïve group was more accurate with vowel contrasts than with tones, suggesting that non-tonal language speakers without any Mandarin training are less sensitive to tonal distinction than to vowels. The two learner groups, on the other hand, were highly accurate with all contrasts except for the T2-T3 pair, and achieved significantly higher accuracy than the Naïve group on /li-ly/ and T1-T4. This lends support to the view that experience in Mandarin improves English speakers' sensitivity to tonal distinction, helping them discriminate some tones as accurately as vowels. However, all three groups achieved low accuracy in discriminating T2 and T3, suggesting that this contrast may be inherently difficult and resistant to improvement. This study shows that various factors in addition to the native language experience may affect the perception of non-native vowels and tones.

Perception of American English vowels by sequential Spanish-English bilinguals

Research on American-English (AE) vowel perception by Spanish-English bilinguals has focused on the vowels /i/-/ɪ/ (e.g., in sheep/ship). Other AE vowel contrasts may present perceptual challenges for this population, especially those requiring both spectral and durational discrimination. We used Event-Related Potentials (ERPs), MMN (Mismatch Negativity) and P300, to index discrimination of AE vowels /ɑ/-/ʌ/ by sequential adult Spanish-English bilingual listeners compared to AE monolinguals. Listening tasks were non-attended and attended, and vowels were presented with natural and neutralized durations. Regardless of vowel duration, bilingual listeners showed no MMN to unattended sounds, and P300 responses were elicited to /ɑ/ but not /ʌ/ in the attended condition. Monolingual listeners showed pre-attentive discrimination (MMN) for /ɑ/ only; while both vowels elicited P300 responses when attended. Findings suggest that Spanish-English bilinguals recruit attentional and cognitive resources enabling native-like use of both spectral and durational cues to discriminate between AE vowels /ɑ/ and /ʌ/.

Learning the Marshallese Phonological System: The Role of Cross-language Similarity on the Perception and Production of Secondary Articulations

The current study determines the influence of cross-language similarity on native English speakers' perception and production of Marshallese consonant contrasts. Marshallese provides a unique opportunity to study this influence because all Marshallese consonants have a secondary articulation. Results of discrimination and production tasks indicate that learners more easily acquire sounds if they are perceptually less similar to native language phonemes. In addition, the degree of cross-language similarity seemed to affect perception and production and may also interact with the effect of orthography.

Acoustical analysis of Canadian French word-final vowels in varying phonetic contexts

This study analyzed Canadian French (CF) vowels /i y ø e ɛ o u a/ in word-final position. Of particular interest was the stability of /e-ɛ/; although some dialects of French have merged /e-ɛ/ to /e/ in word-final context, this contrast is maintained in CF. The present study investigated the stability of this contrast in various preceding phonetic contexts and in lexical vs morphological contrasts. Results showed that the contrast was maintained by all four speakers, although to varying degrees.

Children's perception of conversational and clear American-English vowels in noise

PURPOSE

Much of a child's day is spent listening to speech in the presence of background noise. Although accurate vowel perception is important for listeners' accurate speech perception and comprehension, little is known about children's vowel perception in noise. Clear speech is a speech style frequently used by talkers in the presence of noise. This study investigated children's identification of vowels in nonsense words in noise and examined whether adults' use of clear speech would result in the children's more accurate vowel identification.

METHOD

Two female American-English (AE) speaking adults were recorded producing the nonsense word /gəbVpə/ with AE vowels /ɛ-æ-ɑ-ʌ/ in phrases in conversational and clear speech. These utterances were presented to 15 AE-speaking children (ages 5.0-8.5 years) at a signal-to-noise ratio of -6 dB. The children repeated the utterances.

RESULTS

Clear-speech vowels were repeated significantly more accurately (87%) than conversational-speech vowels (59%), suggesting that clear speech aids children's vowel identification. Children repeated one talker's vowels more accurately than the other's, and front vowels more accurately than central and back vowels.

CONCLUSION

The findings support the use of clear speech for enhancing adult-to-child communication in AE in noisy environments.

A cross-dialectal acoustic comparison of vowels in Northern and Southern British English

This study compares the duration and first two formants (F1 and F2) of 11 nominal monophthongs and five nominal diphthongs in Standard Southern British English (SSBE) and a Northern English dialect. F1 and F2 trajectories were fitted with parametric curves using the discrete cosine transform (DCT) and the zeroth DCT coefficient represented formant trajectory means and the first DCT coefficient represented the magnitude and direction of formant trajectory change to characterize vowel inherent spectral change (VISC). Cross-dialectal comparisons involving these measures revealed significant differences for the phonologically back monophthongs /ɒ, ɔː, ʊ, uː/ and also /зː/ and the diphthongs /eɪ, əʊ, aɪ, ɔɪ/. Most cross-dialectal differences are in zeroth DCT coefficients, suggesting formant trajectory means tend to characterize such differences, while first DCT coefficient differences were more numerous for diphthongs. With respect to VISC, the most striking differences are that /uː/ is considerably more diphthongized in the Northern dialect and that the F2 trajectory of /əʊ/ proceeds in opposite directions in the two dialects. Cross-dialectal differences were found to be largely unaffected by the consonantal context in which the vowels were produced. The implications of the results are discussed in relation to VISC, consonantal context effects and speech perception.

Influences of listeners' native and other dialects on cross-language vowel perception

This paper examines to what extent acoustic similarity between native and non-native vowels predicts non-native vowel perception and whether this process is influenced by listeners' native and other non-native dialects. Listeners with Northern and Southern British English dialects completed a perceptual assimilation task in which they categorized tokens of 15 Dutch vowels in terms of English vowel categories. While the cross-language acoustic similarity of Dutch vowels to English vowels largely predicted Southern listeners' perceptual assimilation patterns, this was not the case for Northern listeners, whose assimilation patterns resembled those of Southern listeners for all but three Dutch vowels. The cross-language acoustic similarity of Dutch vowels to Northern English vowels was re-examined by incorporating Southern English tokens, which resulted in considerable improvements in the predicting power of cross-language acoustic similarity. This suggests that Northern listeners' assimilation of Dutch vowels to English vowels was influenced by knowledge of both native Northern and non-native Southern English vowel categories. The implications of these findings for theories of non-native speech perception are discussed.

Perceptual confusions of American-English vowels and consonants by native Arabic bilinguals

This study investigated the perception of American-English (AE) vowels and consonants by young adults who were either (a) early Arabic-English bilinguals whose native language was Arabic or (b) native speakers of the English dialects spoken in the United Arab Emirates (UAE), where both groups were studying. In a closed-set format, participants were asked to identify 12 AE vowels presented in /hVd/ context and 20 AE consonants (C) in three vocalic contexts: /aCa/, /iCi/, and /uCu/. Both native Arabic and native English groups demonstrated high accuracy in identification of vowels (70 and 80% correct, respectively) and consonants (94 and 95% correct, respectively). For both groups, the least-accurately identified vowels were /o/, /(see text)/, /ae/, while most consonant errors were found for /(see text)/, which was most frequently confused with /v/. However, for both groups, identification of /(see text)/ was vocalic-context dependent, with most errors occurring in liCil context and fewest errors occurring in luCu/ context. Lack of significant group differences suggests that speech sound identification patterns, including phonetic context effects for /(see text)/, were influenced more by the local English dialects than by listeners' Arabic language background. The findings also demonstrate consistent perceptual error patterns among listeners despite considerable variation in their native and second language dialectal backgrounds.

A study of high front vowels with articulatory data and acoustic simulations

The purpose of this study is to test a methodology for describing the articulation of vowels. High front vowels are a test case because some theories suggest that high front vowels have little cross-linguistic variation. Acoustic studies appear to show counterexamples to these predictions, but purely acoustic studies are difficult to interpret because of the many-to-one relation between articulation and acoustics. In this study, vocal tract dimensions, including constriction degree and position, are measured from cinéradiographic and x-ray data on high front vowels from three different languages (North American English, French, and Mandarin Chinese). Statistical comparisons find several significant articulatory differences between North American English /i/ and Mandarin Chinese and French /i/. In particular, differences in constriction degree were found, but not constriction position. Articulatory synthesis is used to model the acoustic consequences of some of the significant articulatory differences, finding that the articulatory differences may have the acoustic consequences of making the latter languages' /i/ perceptually sharper by shifting the frequencies of F(2) and F(3) upwards. In addition, the vowel /y/ has specific articulations that differ from those for /i/, including a wider tongue constriction, and substantially different acoustic sensitivity functions for F(2) and F(3).

Dialect effects in speech perception: the role of vowel duration in Parisian French and Swiss French

The current experiments examined how native Parisian French and native Swiss French listeners use vowel duration in perceiving the /[character: see text]/-/o/ contrast. In both Parisian and Swiss French /ol is longer than /[character: see text]/, but the difference is relatively large in Swiss French and quite small in Parisian French. In Experiment I we found a parallel effect in perception. For native listeners of both dialects, the perceived best exemplars of /o/ were longer than those of /[character: see text]/. However, there was a substantial difference in best-exemplar duration for /[character: see text]/ and /o/ for Swiss French listeners, but only a small difference in best-exemplar duration for Parisian French listeners. In Experiment 2 we found that this precise pattern depended not only on the native dialect of the listeners, but also on whether the stimuli being judged had the detailed acoustic characteristics of the native dialect. These findings indicate that listeners use fine-grained information in the speech signal in a dialect-specific manner when mapping the acoustic signal onto vowel categories of their language.

Stronger accent following a stroke: the case of a trilingual with aphasia

This study documents patterns of change in speech production in a multilingual with aphasia following a cerebrovascular accident (CVA). EC, a right-handed Hebrew-English-French trilingual man, had a left fronto-temporo-parietal CVA, after which he reported that his (native) Hebrew accent became stronger in his (second language) English. Recordings of his pre- and post-CVA speech permitted an investigation of changes in his accent. In sentence- and segment-listening tasks, native American English listeners (n = 13 and 15, respectively) judged EC's pre- and post-CVA speech. EC's speech was perceived as more foreign-accented, slow, strained and hesitant, but not less intelligible, post-CVA. Acoustic analysis revealed less coarticulation and longer vowel- and word-durations post-CVA. This case extends knowledge about perceptual and acoustic changes in speech production in multilinguals following CVAs. It is suggested that EC's stronger accent post-CVA may have resulted from damage to the neuronal networks that led to impairment in his other language domains.

Context-specific acoustic differences between Peruvian and Iberian Spanish vowels

This paper examines four acoustic properties (duration F0, F1, and F2) of the monophthongal vowels of Iberian Spanish (IS) from Madrid and Peruvian Spanish (PS) from Lima in various consonantal contexts (/s/, /f/, /t/, /p/, and /k/) and in various phrasal contexts (in isolated words and sentence-internally). Acoustic measurements on 39 speakers, balanced by dialect and gender, can be generalized to the following differences between the two dialects. The vowel /a/ has a lower first formant in PS than in IS by 6.3%. The vowels /e/ and /o/ have more peripheral second-formant (F2) values in PS than in IS by about 4%. The consonant /s/ causes more centralization of the F2 of neighboring vowels in IS than in PS. No dialectal differences are found for the effect of phrasal context. Next to the between-dialect differences in the vowels, the present study finds that /s/ has a higher spectral center of gravity in PS than in IS by about 10%, that PS speakers speak slower than IS speakers by about 9%, and that Spanish-speaking women speak slower than Spanish-speaking men by about 5% (irrespective of dialect).

Production of phonetic and phonological contrast by heritage speakers of Mandarin

This study tested the hypothesis that heritage speakers of a minority language, due to their childhood experience with two languages, would outperform late learners in producing contrast: language-internal phonological contrast, as well as cross-linguistic phonetic contrast between similar, yet acoustically distinct, categories of different languages. To this end, production of Mandarin and English by heritage speakers of Mandarin was compared to that of native Mandarin speakers and native American English-speaking late learners of Mandarin in three experiments. In experiment 1, back vowels in Mandarin and English were produced distinctly by all groups, but the greatest separation between similar vowels was achieved by heritage speakers. In experiment 2, Mandarin aspirated and English voiceless plosives were produced distinctly by native Mandarin speakers and heritage speakers, who both put more distance between them than late learners. In experiment 3, the Mandarin retroflex and English palato-alveolar fricatives were distinguished by more heritage speakers and late learners than native Mandarin speakers. Thus, overall the hypothesis was supported: across experiments, heritage speakers were found to be the most successful at simultaneously maintaining language-internal and cross-linguistic contrasts, a result that may stem from a close approximation of phonetic norms that occurs during early exposure to both languages.

Production of French vowels by American-English learners of French: language experience, consonantal context, and the perception-production relationship

Second-language (L2) speech perception studies have demonstrated effects of language background and consonantal context on categorization and discrimination of vowels. The present study examined the effects of language experience and consonantal context on the production of Parisian French (PF) vowels by American English (AE) learners of French. Native AE speakers repeated PF vowels /i-y-u-oe-a/ in bilabial /bVp/ and alveolar /dVt/ contexts embedded in the phrase /raCVCa/. Three AE groups participated: speakers without French experience (NoExp), speakers with formal French experience (ModExp), and speakers with formal-plus-immersion experience (HiExp). Production accuracy was assessed by native PF listeners' judgments and by acoustic analysis. PF listeners identified L2 learners' productions more accurately when the learners had extensive language experience, although /y-u-oe/ by even HiExp speakers were frequently misidentified. A consonantal context effect was evident, including /u/ produced by ModExp misidentified more often in alveolar context than in bilabial, and /y/ misidentified more often in bilabial than in alveolar context, suggesting cross-language transfer of coarticulatory rules. Overall, groups distinguished front rounded /y/ from /u/ in production, but often in a non-native manner, e.g., producing /y/ as /(j)u/. Examination of perceptual data from the same individuals revealed a modest, yet complex, perception-production link for L2 vowels.

Conversational and clear speech intelligibility of /bVd/ syllables produced by native and non-native English speakers

The ability of native and non-native speakers to enhance intelligibility of target vowels by speaking clearly was compared across three talker groups: monolingual English speakers and native Spanish speakers with either an earlier or a later age of immersion in an English-speaking environment. Talkers produced the target syllables "bead, bid, bayed, bed, bad" and "bod" in 'conversational' and clear speech styles. The stimuli were presented to native English-speaking listeners in multi-talker babble with signal-to-noise ratios of -8 dB for the monolingual and early learners and -4 dB for the later learners. The monolinguals and early learners of English showed a similar average clear speech benefit, and the early learners showed equal or greater intelligibility than monolinguals for most target vowels. The 4-dB difference in signal-to-noise ratio yielded approximately equal average intelligibility for the monolinguals and later learners. The average clear speech benefit was smallest for the later learners, and a significant clear speech decrement was obtained for the target syllable "bid." These results suggest that later learners of English as a second language may be less able than monolinguals to accommodate listeners in noisy environments, due to a reduced ability to improve intelligibility by speaking more clearly.

On the assimilation-discrimination relationship in American English adults' French vowel learning

A quantitative "cross-language assimilation overlap" method for testing predictions of the Perceptual Assimilation Model (PAM) was implemented to compare results of a discrimination experiment with the listeners' previously reported assimilation data. The experiment examined discrimination of Parisian French (PF) front rounded vowels /y/ and /oe/. Three groups of American English listeners differing in their French experience (no experience [NoExp], formal experience [ModExp], and extensive formal-plus-immersion experience [HiExp]) performed discrimination of PF /y-u/, /y-o/, /oe-o/, /oe-u/, /y-i/, /y-epsilon/, /oe-epsilon/, /oe-i/, /y-oe/, /u-i/, and /a-epsilon/. Vowels were in bilabial /rabVp/ and alveolar /radVt/ contexts. More errors were found for PF front vs back rounded vowel pairs (16%) than for PF front unrounded vs rounded pairs (2%). Overall, ModExp listeners did not perform more accurately (11% errors) than NoExp listeners (13% errors). Extensive immersion experience, however, was associated with fewer errors (3%) than formal experience alone, although discrimination of PF /y-u/ remained relatively poor (12% errors) for HiExp listeners. More errors occurred on pairs involving front vs back rounded vowels in alveolar context (20% errors) than in bilabial (11% errors). Significant correlations were revealed between listeners' assimilation overlap scores and their discrimination errors, suggesting that the PAM may be extended to second-language (L2) vowel learning.

A cross-dialect acoustic description of vowels: Brazilian and European Portuguese

This paper examines four acoustic correlates of vowel identity in Brazilian Portuguese (BP) and European Portuguese (EP): first formant (F1), second formant (F2), duration, and fundamental frequency (F0). Both varieties of Portuguese display some cross-linguistically common phenomena: vowel-intrinsic duration, vowel-intrinsic pitch, gender-dependent size of the vowel space, gender-dependent duration, and a skewed symmetry in F1 between front and back vowels. Also, the average difference between the vocal tract sizes associated with /i/ and /u/, as measured from formant analyses, is comparable to the average difference between male and female vocal tract sizes. A language-specific phenomenon is that in both varieties of Portuguese the vowel-intrinsic duration effect is larger than in many other languages. Differences between BP and EP are found in duration (BP has longer stressed vowels than EP), in F1 (the lower-mid front vowel approaches its higher-mid counterpart more closely in EP than in BP), and in the size of the intrinsic pitch effect (larger for BP than for EP).

Cross-language categorization of French and German vowels by naive American listeners

American English (AE) speakers' perceptual assimilation of 14 North German (NG) and 9 Parisian French (PF) vowels was examined in two studies using citation-form disyllables (study 1) and sentences with vowels surrounded by labial and alveolar consonants in multisyllabic nonsense words (study 2). Listeners categorized multiple tokens of each NG and PF vowel as most similar to selected AE vowels and rated their category "goodness" on a nine-point Likert scale. Front, rounded vowels were assimilated primarily to back AE vowels, despite their acoustic similarity to front AE vowels. In study 1, they were considered poorer exemplars of AE vowels than were NG and PF back, rounded vowels; in study 2, front and back, rounded vowels were perceived as similar to each other. Assimilation of some front, unrounded and back, rounded NG and PF vowels varied with language, speaking style, and consonantal context. Differences in perceived similarity often could not be predicted from context-specific cross-language spectral similarities. Results suggest that listeners can access context-specific, phonetic details when listening to citation-form materials, but assimilate non-native vowels on the basis of context-independent phonological equivalence categories when processing continuous speech. Results are interpreted within the Automatic Selective Perception model of speech perception.

The role of native-language phonology in the auditory word identification and visual word recognition of Russian-English bilinguals

Does native language phonology influence visual word processing in a second language? This question was investigated in two experiments with two groups of Russian-English bilinguals, differing in their English experience, and a monolingual English control group. Experiment 1 tested visual word recognition following semantic categorization of words containing four phonological vowel contrasts (/i/-/u/,/I/-/A/,/i/-/I/,/epsilon/-/ae/). Experiment 2 assessed auditory identification accuracy of words containing these four contrasts. Both bilingual groups demonstrated reduced accuracy in auditory identification of two English vowel contrasts absent in their native phonology (/i/-/I/,epsilon/-/ae/). For late- bilinguals, auditory identification difficulty was accompanied by poor visual word recognition for one difficult contrast (/i/-/I/). Bilinguals' visual word recognition moderately correlated with their auditory identification of difficult contrasts. These results indicate that native language phonology can play a role in visual processing of second language words. However, this effect may be considerably constrained by orthographic systems of specific languages.

Language experience and consonantal context effects on perceptual assimilation of French vowels by American-English learners of French

Recent research has called for an examination of perceptual assimilation patterns in second-language speech learning. This study examined the effects of language learning and consonantal context on perceptual assimilation of Parisian French (PF) front rounded vowels /y/ and /oe/ by American English (AE) learners of French. AE listeners differing in their French language experience (no experience, formal instruction, formal-plus-immersion experience) performed an assimilation task involving PF /y, oe, u, o, i, epsilon, a/ in bilabial /rabVp/ and alveolar /radVt/ contexts, presented in phrases. PF front rounded vowels were assimilated overwhelmingly to back AE vowels. For PF /oe/, assimilation patterns differed as a function of language experience and consonantal context. However, PF /y/ revealed no experience effect in alveolar context. In bilabial context, listeners with extensive experience assimilated PF /y/ to (j)u less often than listeners with no or only formal experience, a pattern predicting the poorest /u-y/ discrimination for the most experienced group. An "internal consistency" analysis indicated that responses were most consistent with extensive language experience and in bilabial context. Acoustical analysis revealed that acoustical similarities among PF vowels alone cannot explain context-specific assimilation patterns. Instead it is suggested that native-language allophonic variation influences context-specific perceptual patterns in second-language learning.

Acoustic and perceptual similarity of Japanese and American English vowels

Acoustic and perceptual similarities between Japanese and American English (AE) vowels were investigated in two studies. In study 1, a series of discriminant analyses were performed to determine acoustic similarities between Japanese and AE vowels, each spoken by four native male speakers using F1, F2, and vocalic duration as input parameters. In study 2, the Japanese vowels were presented to native AE listeners in a perceptual assimilation task, in which the listeners categorized each Japanese vowel token as most similar to an AE category and rated its goodness as an exemplar of the chosen AE category. Results showed that the majority of AE listeners assimilated all Japanese vowels into long AE categories, apparently ignoring temporal differences between 1- and 2-mora Japanese vowels. In addition, not all perceptual assimilation patterns reflected context-specific spectral similarity patterns established by discriminant analysis. It was hypothesized that this incongruity between acoustic and perceptual similarity may be due to differences in distributional characteristics of native and non-native vowel categories that affect the listeners' perceptual judgments.

Training Japanese listeners to perceive American English vowels: influence of training sets

PURPOSE

Studies on speech perception training have shown that adult 2nd language learners can learn to perceive non-native consonant contrasts through laboratory training. However, research on perception training for non-native vowels is still scarce, and none of the previous vowel studies trained more than 5 vowels. In the present study, the influence of training set sizes was investigated by training native Japanese listeners to identify American English (AE) vowels.

METHOD

Twelve Japanese learners of English were trained 9 days either on 9 AE monophthongs (fullset training group) or on the 3 more difficult vowels (subset training group). Five listeners served as controls and received no training. Performance of listeners was assessed before and after training as well as 3 months after training was completed.

RESULTS

Results indicated that (a) fullset training using 9 vowels in the stimulus set improved average identification by 25%; (b) listeners in both training groups generalized improvement to untrained words and tokens spoken by novel speakers; and (c) both groups maintained improvement after 3 months. However, the subset group never improved on untrained vowels.

CONCLUSIONS

Training protocols for learning non-native vowels should present a full set of vowels and should not focus only on the more difficult vowels.