Native American English Research Articles

Similar frequency of the McGurk effect in large samples of native Mandarin Chinese and American English speakers.

Humans combine visual information from mouth movements with auditory information from the voice to recognize speech. A common method for assessing multisensory speech perception is the McGurk effect: When presented with particular pairings of incongruent auditory and visual speech syllables (e.g., the auditory speech sounds for "ba" dubbed onto the visual mouth movements for "ga"), individuals perceive a third syllable, distinct from the auditory and visual components. Chinese and American cultures differ in the prevalence of direct facial gaze and in the auditory structure of their languages, raising the possibility of cultural- and language-related group differences in the McGurk effect. There is no consensus in the literature about the existence of these group differences, with some studies reporting less McGurk effect in native Mandarin Chinese speakers than in English speakers and others reporting no difference. However, these studies sampled small numbers of participants tested with a small number of stimuli. Therefore, we collected data on the McGurk effect from large samples of Mandarin-speaking individuals from China and English-speaking individuals from the USA (total n = 307) viewing nine different stimuli. Averaged across participants and stimuli, we found similar frequencies of the McGurk effect between Chinese and American participants (48 vs. 44 %). In both groups, we observed a large range of frequencies both across participants (range from 0 to 100 %) and stimuli (15 to 83 %) with the main effect of culture and language accounting for only 0.3 % of the variance in the data. High individual variability in perception of the McGurk effect necessitates the use of large sample sizes to accurately estimate group differences.

The Role of Secondary-Stressed and Unstressed-Unreduced Syllables in Word Recognition: Acoustic and Perceptual Studies with Russian Learners of English.

The importance of secondary-stressed (SS) and unstressed-unreduced (UU) syllable accuracy for spoken word recognition in English is as yet unclear. An acoustic study first investigated Russian learners' of English production of SS and UU syllables. Significant vowel quality and duration reductions in Russian-spoken SS and UU vowels were found, likely due to a transfer of native phonological features. Next, a cross-modal phonological priming technique combined with a lexical decision task assessed the effect of inaccurate SS and UU syllable productions on native American English listeners' speech processing. Inaccurate UU vowels led to significant inhibition of lexical access, while reduced SS vowels revealed less interference. The results have implications for understanding the role of SS and UU syllables for word recognition and English pronunciation instruction.

Nonnative audiovisual speech perception in noise: dissociable effects of the speaker and listener.

Nonnative speech poses a challenge to speech perception, especially in challenging listening environments. Audiovisual (AV) cues are known to improve native speech perception in noise. The extent to which AV cues benefit nonnative speech perception in noise, however, is much less well-understood. Here, we examined native American English-speaking and native Korean-speaking listeners' perception of English sentences produced by a native American English speaker and a native Korean speaker across a range of signal-to-noise ratios (SNRs;−4 to −20 dB) in audio-only and audiovisual conditions. We employed psychometric function analyses to characterize the pattern of AV benefit across SNRs. For native English speech, the largest AV benefit occurred at intermediate SNR (i.e. −12 dB); but for nonnative English speech, the largest AV benefit occurred at a higher SNR (−4 dB). The psychometric function analyses demonstrated that the AV benefit patterns were different between native and nonnative English speech. The nativeness of the listener exerted negligible effects on the AV benefit across SNRs. However, the nonnative listeners' ability to gain AV benefit in native English speech was related to their proficiency in English. These findings suggest that the native language background of both the speaker and listener clearly modulate the optimal use of AV cues in speech recognition.

Identification and response latencies for Mandarin-accented isolated words in quiet and in noise

This study compared the intelligibility of native and foreign-accented American English speech presented in quiet and mixed with two different levels of background noise. Two native American English speakers and two native Mandarin Chinese speakers for whom English is a second language read three 50-word lists of phonetically balanced words (Stuart, 2004). The words were mixed with noise at three different signal-to-noise levels—no noise (quiet), SNR + 10 dB (signal 10 dB louder than noise) and SNR 0 (signal and noise at equal loudness). These stimuli were presented to ten native American English listeners who were simply asked to repeat the words they heard the speakers say. Listener response latencies were measured. The results showed that for both native and accented speech, response latencies increased as the noise level increased. For words identified correctly, response times to accented speech were longer than for native speech but the noise conditions affected both types equally. For words judged incorrectly, however, the noise conditions increased latencies for accented speech more than for native speech. Overall, these results support the notion that processing accented speech requires more cognitive effort than processing native speech.

Perceptual distinctiveness of dental vs. palatal sibilants in different vowel contexts

This paper reports a similarity rating experiment and a speeded AX discrimination experiment to test the perceptual distinctiveness of dental vs. palatal sibilants in different vowel contexts. The stimuli were pairs of CV sequences where the onsets were [s, ts, tsʰ] vs. [ɕ, tɕ, tɕʰ] as in Mandarin Chinese and the vowels were [i, a, o]; the durations of the consonants and vowels were set to values close to those in natural speech; the inter-stimulus-interval was set at 100ms to facilitate responses based on psychoacoustic similarity. A significant effect of vowel contexts was observed in the similarity rating by 20 native American English speakers, whereby the dental vs. palatal sibilants were judged to be the least distinct in the [i] context. A similar pattern was observed in the speeded AX discrimination, whereby the [i] context introduced slower “different” responses than other vowels. In general, this study supports the view that the perceptual distinctiveness of a consonant pair may vary with differe...

The rhythm of Aviation English by Native American English speakers

Air traffic controllers (ATC) and pilots at international airports must speak Aviation English (AE). Native and non-native English speakers alike must learn and effectively communicate using this technical language based on standard English. This project calculates the rhythmic profile of Native Speaker Aviation English (NSAE), which serves as the target for learners of AE and against which potential communication failures can be evaluated. NSAE rhythmic profile can be contrasted with the first language (L1) prosody to evaluate learner AE production and model training methods for specific L1 AE learners. NSAE generally exhibits flat intonational contours, so we focus on rhythm metrics. Our previous study’s findings demonstrated that NSAE metrics pattern differently than standard American English, falling between “stress-timed” and “syllable-timed” languages. Rhythm metrics based on consonant and vowel duration are affected by AE’s lack of function words (i.e., fewer reducible vowels), standard phraseology (producing prosodic chunking), and rapid speech rate (reflecting compressibility differential between vowel and consonant segments). We are training an automatic speech aligner to segment ATC NSAE and calculating a baseline for American NSAE using qualitative metrics (Ramus 2000; Low et al., 2000; Dellwo 2006). We will present our findings on how NSAE patterns with similarly evaluated languages.

Can adjustment to accented speech affect native language perception?

The human auditory system can quickly accommodate foreign-accented speech. However, the cognitive mechanisms underlying perceptual adjustment to non-native speech are not fully understood. The current study examined the perceptual consequences of adaptation toward foreign-accented speech on native language perception. Native English speakers performed an auditory shadowing task on word-length utterances in English. There were four blocks of trials. The words in the critical block (Block 3) were spoken by either a native American English speaker or a native Spanish speaker. The speaker in flanking blocks (Blocks 1–2, 4) was the same speaker, a different speaker with the same accent, or a different speaker with a different accent. Shadowing response times in the critical block were used to assess rapid perceptual adjustment and readjustment. Results showed that the nature of the preceding context influenced response times. Response times for items in the first quartile of the critical block were reliably slower when accent and talker changed than when accent and talker remained constant. These findings suggest that listeners develop perceptual expectations about ongoing speech, which when violated incur a short-term processing cost even for spoken words in the listeners’ native language.

A Cognitively Grounded Measure of Pronunciation Distance

In this study we develop pronunciation distances based on naive discriminative learning (NDL). Measures of pronunciation distance are used in several subfields of linguistics, including psycholinguistics, dialectology and typology. In contrast to the commonly used Levenshtein algorithm, NDL is grounded in cognitive theory of competitive reinforcement learning and is able to generate asymmetrical pronunciation distances. In a first study, we validated the NDL-based pronunciation distances by comparing them to a large set of native-likeness ratings given by native American English speakers when presented with accented English speech. In a second study, the NDL-based pronunciation distances were validated on the basis of perceptual dialect distances of Norwegian speakers. Results indicated that the NDL-based pronunciation distances matched perceptual distances reasonably well with correlations ranging between 0.7 and 0.8. While the correlations were comparable to those obtained using the Levenshtein distance, the NDL-based approach is more flexible as it is also able to incorporate acoustic information other than sound segments.

Measuring Foreign Accent Strength in English

With an eye toward measuring the strength of foreign accents in American English, we evaluate the suitability of a modified version of the Levenshtein distance for comparing (the phonetic transcriptions of) accented pronunciations. Although this measure has been used successfully inter alia to study the differences among dialect pronunciations, it has not been applied to studying foreign accents. Here, we use it to compare the pronunciation of non-native English speakers to native American English speech. Our results indicate that the Levenshtein distance is a valid native-likeness measurement, as it correlates strongly (r = -0.81) with the average “native-like” judgments given by more than 1000 native American English raters.

Prevalence of Vocal Fry in Young Adult Male American English Speakers

The purpose of this study was to assess possible gender differences in the prevalence of vocal fry in the voices of young male college students. Results were compared with previously published findings derived from a matched sample of female speakers. Thirty-four male college students, native American English speakers, produced speech samples in two speaking conditions: (1) sustained isolated vowel /a/ and (2) reading task. Data analyses included perceptual evaluations by two licensed speech-language pathologists. Results showed that vocal fry was perceived significantly more frequently in sentences than in isolated vowel productions. When vocal fry occurred in sentences, it was detected significantly more often in sentence-final position than in initial- and/or mid-sentence position. Furthermore, the prevalence of vocal fry in sentences was significantly lower for male speakers than has previously been reported for female speakers. Possible physiological and sociolinguistic explanations are discussed.

Effects of linguistic background and noise on perception of fricatives

This study examined how native American English (AE) speakers perceived fricatives spoken by native AE and Bangladeshi Bengali (BB) speakers in quiet and noise. Participants included seven normal-hearing adults between 20 to 26 years of age. Participants listened to speech tokens of five fricatives, /s/, /z/, /∫/, /f/, and /v/ in the initial, medial, and final positions in the context of the point vowels /a/, /u/, /i/. Multitalker babble (MTB), speech noise, and three narrow bands of noise, 1000–2000 Hz, 2000–4000 Hz, and 500–5000 Hz at 45 dB SPL, 65 dB SPL and 85 dB SPL were used. The results suggested that listeners perceived fricatives significantly better when spoken by AE compared to BB speakers, and in quiet than in noise, especially in MTB. Listeners had the most difficulty with /z/, followed by /s/, /v/, /f, and /∫/ respectively, when tokens were spoken by BB speakers. This study may have implications for accent reduction therapy as well as for teaching English to English-language learners, especially when the phonology of the learners’ native language differs greatly from that of AE. Further studies are warranted especially due to an increasingly growing non-AE speaking population in the United States.

Effects of noise and speaker's language background on plosive perception

This study examined the effect of speakers' language background and noise on the perception of American English (AE) plosives. Six normal-hearing, young-adults volunteered for the study. Participants listened to speech tokens of six plosives, /p/, /b/, /t/, /d/, /k/, and /g/ in the initial, medial, and final positions in the context of three vowels, /a/, /i/, and /u/, spoken by native Bangladeshi Bengali (BB) and AE speakers. Tokens were presented at 45, 65, and 65 dB SPL, either in quiet or noise. Multitalker babble, speech noise, and 1000–2000 Hz, 2000–4000 Hz, and 500–5000 Hz noise bands were used as noise. Significant differences were found with all noise types across both language backgrounds; the most difficult noise type condition being the multitalker babble. Listeners performed the best at 65 dB SPL. Listeners perceived plosives spoken by AE than BB speakers with significantly greater accuracy, more so in noise, except in the final positions. For BB-spoken tokens, listeners had the most difficulty with voicing and aspiration features. Voiceless sounds were easily confused with voiced, especially in the initial positions. This study has significant implications for accent reduction therapy as well as for teaching English to English Language Learner's. Further studies are warranted.

Automatic Accent Assessment Using Phonetic Mismatch and Human Perception

In this study, a new algorithm for automatic accent evaluation of native and non-native speakers is presented. The proposed system consists of two main steps: alignment and scoring. In the alignment step, the speech utterance is processed using a Weighted Finite State Transducer (WFST) based technique to automatically estimate the pronunciation mismatches (substitutions, deletions, and insertions). Subsequently, in the scoring step, two scoring systems which utilize the pronunciation mismatches from the alignment phase are proposed: (i) a WFST-scoring system to measure the degree of accentedness on a scale from -1 (non-native like) to +1 (native like), and a (ii) Maximum Entropy (ME) based technique to assign perceptually motivated scores to pronunciation mismatches. The accent scores provided from the WFST-scoring system as well as the ME scoring system are termed as the WFST and P-WFST (perceptual WFST) accent scores, respectively. The proposed systems are evaluated on American English (AE) spoken by native and non-native (native speakers of Mandarin-Chinese) speakers from the CU-Accent corpus. A listener evaluation of 50 Native American English (N-AE) was employed to assist in validating the performance of the proposed accent assessment systems. The proposed P-WFST algorithm shows higher and more consistent correlation with human evaluated accent scores, when compared to the Goodness Of Pronunciation (GOP) measure. The proposed solution for accent classification and assessment based on WFST and P-WFST scores show that an effective advancement is possible which correlates well with human perception.

Prosodic boundary information modulates phonetic categorization

Categorical perception experiments were performed on an English /b-p/ voice onset time (VOT) continuum with native (American English) and non-native (Korean) listeners to examine whether and how phonetic categorization is modulated by prosodic boundary and language experience. Results demonstrated perceptual shifting according to prosodic boundary strength: A longer VOT was required to identify a sound as /p/ after an intonational phrase than a word boundary, regardless of the listeners' language experience. This suggests that segmental perception is modulated by the listeners' computation of an abstract prosodic structure reflected in phonetic cues of phrase-final lengthening and domain-initial strengthening, which are common across languages.

English vowels produced by Cantonese–English bilingual speakers

The present study attempted to test the postulate that sounds of a foreign language that are familiar can be produced with less accuracy than sounds that are new to second language (L2) learners. The first two formant frequencies (F1 and F2) were obtained from the 11 English monophthong vowels produced by 40 Cantonese–English (CE) bilingual and 40 native American English monolingual speakers. Based on F1 and F2, compact-diffuse (C-D) and grave-acute (G-A) values, and Euclidean Distance (ED) associated with the English vowels were evaluated and correlated with the perceived amount of accent present in the vowels. Results indicated that both male and female CE speakers exhibited different vowel spaces compared to their AE counterparts. While C-D and G-A indicated that acquisition of familiar and new vowels were not particularly different, ED values suggested better performance in CE speakers’ productions of familiar vowels over new vowels. In conclusion, analyses based on spectral measurements obtained from the English vowel sounds produced by CE speakers did not provide favourable evidence to support the Speech Learning Model (SLM) proposed by . Nevertheless, for both familiar and new sounds, English back vowels were found to be produced with greater inaccuracy than English front vowels.

Perception of American English final consonants by speakers of New York-Dominican Spanish

The English language uses many final consonants and final clusters to convey meaning, especially for morphological endings. The Spanish language employs fewer final consonants than the English language, and Caribbean Spanish speakers treat many final consonants as optional. In this experiment, speakers originating from the Dominican Republic (N = 25) participated in a listening task in which they had to identify final consonants in fast and clear sentences in English (stimulus corpus Ito, K, 2011). A small group of native American English speakers was tested, and performed at ceiling. Spanish-speaking participants' performance on the experimental task varied from 40% to native-like accuracy and was statistically different from the native speakers’ performance (Mann Whitney U = 8, p < .003). In addition, Spanish-speaking pariticpants’ performance on the final consonant perception task correlated strongly with performance on a standardized aural/oral language battery known as the Versant Test (Pearson Corp, 2011)(r = .76, p < .001); performance also correlated strongly with age of acquisition. The coarticulation of adjacent speech sounds played a role in which consonants were most difficult to perceive. Future directions, including the current testing of speakers of Puerto Rican Spanish, Kannada and Russian, and implications for intervention, will be discussed.

Native Catalan learners' perception and production of English vowels

This paper reports two experiments on nonnative vowel perception and production. In Experiment 1, three groups of Catalan learners varying in English proficiency were tested on their ability to discriminate seven Catalan–English (C–E) and four English–English (E–E) vowel contrasts. The vowel contrasts were natural speech tokens obtained from native Catalan and native American English speakers. On average, listeners distinguished the C–E /i–ɪ/ contrast relatively well, and they could partially distinguish /i–i/, /u–u/, and /a–ɑ/, but they had great difficulty with the /a–ʌ/, /a–æ/ and /ɛ–ɛ/ contrasts. As for the E–E pairs, the learners could discriminate the speech sounds in the /i–ɪ/ and /u–ʊ/ pairs, suggesting that learners may have established new phonetic categories for /ɪ/ and /ʊ/. In Experiment 2, a subgroup of the Catalan learners and a control group of native English speakers produced words containing one of the English vowels /i/, /ɪ/, /ɛ/, /æ/, /ɑ/, /ʌ/, /ʊ/, and /u/. Vowel accuracy was assessed by means of acoustic measurements and by native listener judgments. The acoustic measurements revealed that, in spectral terms, learners produced vowels that were less peripheral than the native English (NE) versions, although there was a tendency for vowel expansion as a function of language proficiency. Vowel duration in the tense–lax vowel pairs also progressed toward more nativelike values in the productions of the more proficient learners. Finally, the NE listener judgments showed that most learners produced the vowels /ɪ/, /æ/, /ʊ/, and /u/ intelligibly but with significantly lower goodness ratings than did the NE speakers.

Lexical and metrical cues for English word segmentation by Mandarin second language learners of English

This paper investigates the roles of lexical cues and metrical cues in word segmentation by Mandarin L2 learners of English with high and low English proficiency. A cross-modal form priming paradigm is adopted in the experiment. In the experiment, 33 participants (16 advanced learners, 17 beginning learners) heard a five-syllable phrase (e.g., anythingcorri, anything is the and corri is the ′), produced by a native American English speaker. After 100 ms, a three-syllable letter string (e.g., the corridor) was shown on the screen. The participants task was to decide whether a target was a real word. The contexts, primes, and targets have real word and non-word version and have either SW or WS (S: strong; W: weak) stress patterns. The results indicate that: (1) Lexical cues are the main strategy for advanced learners; (2) Beginning learners rely more on metrical cues; (3) When the stress pattern of contexts and primes are identical, it took participants less time to response. The results support previous studies that lexical and metrical are the cues listeners would rely on when doing segmentation. Furthermore, the results suggest that the strategies listeners rely on would change as they become more proficient in English.

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.

Automatic estimation of the first subglottal resonance

This letter focuses on the automatic estimation of the first subglottal resonance (Sg1). A database comprising speech and subglottal data of native American English speakers and bilingual Spanish/English speakers was used for the analysis. Data from 11 speakers (five males and six females) were used to derive an empirical relation among the first formant frequency, fundamental frequency, and Sg1. Using the derived relation, Sg1 was automatically estimated from voiced sounds in English and Spanish sentences spoken by 22 different speakers (11 males and 11 females). The error in estimating Sg1 was less than 50 Hz, on average.