Interlanguage Speech Intelligibility Benefit Research Articles

Perception and production of Mandarin-Accented English: The effect of degree of Accentedness on the Interlanguage Speech Intelligibility Benefit for Listeners (ISIB-L) and Talkers (ISIB-T)

Previous research on the Interlanguage Speech Intelligibility Benefit (ISIB) indicates nonnative listeners may have an advantage at understanding nonnative speech of talkers with the same first language (L1) due to shared interlanguage knowledge. The present study offers a comprehensive analysis of various factors that may modulate this advantage, including the proficiency of both the listeners and the talkers, the mapping of phonemes between the L1 and second language (L2), and the acoustic properties of the phones. Accuracy scores on a lexical decision task were used to investigate both native English listeners’ and native Mandarin learners’ of English perception of native English and Mandarin-accented English speech. Results show clear ISIB-L and ISIB-T effects and demonstrate the dynamic nature of ISIB effects, with both being modulated by speaker and listener proficiency. More striking ISIB effects typically occur at the most extreme ends of accentedness. Additionally, an advantage for common-phoneme over unique-phoneme words in nonnative speech was observed. While nonnative productions of common-phoneme words are more accurate than those of unique-phoneme words, for the most accented productions, nonnative listeners are faster to respond to these unique, often mispronounced, productions.The nonnative listener advantage at perceiving nonnative speech depends on various factors, including listener proficiency, speaker proficiency, phoneme characteristics, and the acoustics of specific speech tokens.

When A Nonnative Accent Lets You Spot All the Errors: Examining the Syntactic Interlanguage Benefit.

In our continuously globalizing world, cross-cultural and cross-linguistic communications are far from exceptional. A wealth of research has indicated that the processing of nonnative-accented speech can be challenging for native listeners, both at the level of phonology. However, few online studies have examined the underpinnings of accented speech recognition from the perspective of the nonnative listener, even though behavioral studies indicate that accented input may be easier to process for such individuals (i.e., the interlanguage speech intelligibility benefit. The current EEG study first examined the phonological and syntactic analysis of nonnative-accented speech among nonnative listeners. As such, 30 English learners of Spanish listened to syntactically correct and incorrect Spanish sentences produced in native and nonnative-accented Spanish. The violation in the incorrect sentences was caused by errors that are typical (i.e., gender errors; *la color) or atypical (i.e., number errors; *los color) for English learners of Spanish. Results indicated that nonnative listeners elicit a phonological mismatch negativity (PMN) when attending to speech produced by a native Spanish speaker. Furthermore, the nonnative listeners showed a P600 for all grammatical violations, indicating that they repair all errors regardless of their typicality or the accent in which they are produced. Follow-up analyses compared our novel data to the data of native listeners from the methodologically identical precursor study. These analyses showed that native and nonnative listeners exhibit directionally opposite PMN effects; whereas natives exhibited a larger PMN for English-accented Spanish, nonnatives displayed a larger PMN in response to native Spanish utterances (a classic interlanguage speech intelligibility benefit). An additional difference was observed at the syntactic level: Whereas natives repaired only atypical number errors when they were English-accented, nonnative participants exhibited a P600 in response to all English-accented syntactic errors, regardless of their typicality (a syntactic interlanguage speech intelligibility benefit). Altogether, these results suggest that accented speech is not inherently difficult to process; in fact, nonnatives may benefit from the presence of a nonnative accent. Thus, our data provide some of the first electrophysiological evidence supporting the existence of the classic interlanguage speech intelligibility benefit and its novel syntactic counterpart.

Matched-accent processing: Bulgarian-English bilinguals do not have a processing advantage with Bulgarian-accented English over native English speech

The Interlanguage Speech Intelligibility Benefit (ISIB) hypothesis for Talkers suggests that there is a potential benefit when listening to one’s second language when it is produced in the accent of one’s first language (matched-accent processing). This study explores ISIB, considering listener proficiency. According to second language learning theories, the listener’s second language proficiency determines the extent to which they rely on their first language phonetics, hence the magnitude of ISIB may be affected by listener proficiency. The accuracy and reaction times of Bulgarian-English bilinguals living in the UK were recorded in a lexical decision task. The English stimuli were produced by native English speakers and Bulgarian-English bilinguals. Listeners responded more slowly and less accurately to the matched-accent stimuli than the native English stimuli. In addition, they adapted their reaction times faster to new speakers with a native English accent compared to a Bulgarian accent. However, the listeners with the lowest English proficiency had no advantage in reaction times and accuracy for either accent. The results offer mixed support for ISIB for Talkers, and are consistent with second language learning theories according to which listeners rely less on their native language phonology when their proficiency in the second language has increased.

The Interlanguage Speech Intelligibility Benefit for Turkish Speakers of English

This study is aimed at investigating the Interlanguage Speech Intelligibility Benefit (ISIB) via native English and Turkish listeners’ transcriptions of Turkish talkers’ words with pronunciation errors in English. Speech samples collected from talkers with a Turkish L1 background (N=16) were presented to 33 L1 English and 33 L1 Turkish listeners via an instrument to be filled with the transcriptions of erroneous target words. Results supported matched ISIB for listeners as Turkish talkers were more intelligible to Turkish listeners in a considerably higher number of target words. Similarly, a higher number of target words were more intelligible to Turkish listeners with statistically significant differences. Most of these words had been labelled erroneous due to L1 transfer caused by orthographic interference, mispronunciations of English sounds that do not exist in Turkish, and loanwords found in similar forms in Turkish. Turkish listeners appeared to rely on such cues in Turkish talkers’ speech.

The role of proficiency in the interlanguage speech intelligibility benefit

Previous research indicates nonnative listeners may have an advantage at understanding nonnative speech of talkers with the same L1 due to shared interlanguage knowledge. The present study offers a comprehensive analysis of various factors that may modulate this advantage, including the proficiency of interlocutors, the mapping of phonemes between the L1 and L2, and the acoustic properties of the phonemes. Accuracy scores on a lexical decision task were used to identify whether native Mandarin learners of English are better than native English listeners at perceiving Mandarin-accented English speech, as well as whether they are better at perceiving Mandarin-accented English compared to native English speech. Results indicated an overall native English interlocutor advantage, an advantage for common-phoneme over unique-phoneme words in nonnative speech, and some evidence of gradience in ISIB effects based on the proficiency of talkers and listeners. No strong relationship between type of English input (native or accented) and the ability to understand Mandarin-accented English speech was found. The nonnative listener advantage at perceiving nonnative speech is relatively small and depends on various factors, including listener proficiency, speaker proficiency, phoneme characteristics, and the acoustics of specific speech tokens.

The perception and production of Mandarin-accented English: The role of degree of accentedness in the interlanguage speech intelligibility benefit for talkers and the interlanguage speech intelligibility benefit for listeners

The Interlanguage Speech Intelligibility Benefit for talkers (ISIB-T) claims non-native learners are better at understanding talkers with a shared L1 than they are at understanding native talkers, and the ISIB for listeners (ISIB-L) claims non-native learners are better at understanding talkers with a shared L1 than native speakers are (Hayes-Harb et al., 2008). In the present study, a lexical decision task (including words with shared phonemes in both Mandarin and English, as well as words with phonemes that only occur in English) was used, with accentedness ratings of talkers and listeners collected to investigate whether ISIB is manifested differently for listeners and speakers of different proficiency levels. Accuracy scores and reaction time measures were compared for both L1 (native English) and L2 (high proficiency, low proficiency) groups when listening to strongly Mandarin-accented, weakly Mandarin-accented, and native English speech. Amount of Mandarin-accented English input was also measured. Results showed some gradience in accuracy by degree of accentedness, with trends in the predicted direction suggestive of ISIB-T and ISIB-L effects. In addition, participants were more accurate when listening to words with phonemes shared in Mandarin and English than English-specific phoneme words, an advantage that increased as the strength of speaker accent increased.

The perception of native vs. non-native Danish speech: Bent and Bradlow’s matched interlanguage speech intelligibility benefit revisited

The main objective of the study was to test the applicability of Bent and Bradlow’s matched interlanguage speech intelligibility benefit to the Danish-Polish language pair. We aimed to verify whether it was easier for Polish students of Danish to understand a Danish native speaker or a Polish speaker with a proficient command of Danish. Sixteen Polish students, divided into two groups of eight, listened to two recordings of two Danish texts: one recorded by a native speaker of Danish and the other one — by a native speaker of Polish who is a graduate of Danish philology from a Polish university. Before the experiment, all of the recordings were evaluated in terms of traces of foreign accent using a 7-point Likert scale, the experts being native speakers of Danish. The evaluators assessed the Polish native speaker’s pronunciation as proficient, but they identified certain segmental and suprasegmental features in his speech that are common indicators of a foreign accent in Danish. During the experiment, participants were asked to fill in each recording transcript with twenty missing words. The analysis of the results revealed that the participants scored higher when listening to the text recorded by the Polish speaker. Hence, the matched interlanguage speech intelligibility benefit was observed in a study using Polish as L1 (native language) and Danish as a foreign language. The study may provide a valuable insight into the question of non-native speech perception, foreign-accented speech and the veracity of the matched interlanguage speech intelligibility benefit for the Polish–Danish language pair.

Is there an interlanguage speech credibility benefit?

Abstract Some (though not all) previous studies have documented the interlanguage speech intelligibility benefit (ISIB), i.e. the greater intelligibility of non-native (relative to native) speech to non-native listeners as compared to native listeners. Moreover, some studies (again not all) found that native listeners consider foreign-accented statements as less truthful than native-sounding ones. We join these two lines of research, asking whether foreign-accented statements sound more credible to non-native than to native listeners and whether difficult-to-process (less comprehensible) utterances are less credible. In two experiments we measure the intelligibility, comprehensibility and credibility of native and foreign-accented statements for native listeners and non-native listeners matched or mismatched in L1 with non-native talkers. We find an ISIB in both matched and mismatched non-native listeners, and an analogous matched comprehensibility benefit. However, we obtain no evidence of an interlanguage speech credibility benefit. Instead, both matched and mismatched non-native listeners tend to trust native statements more (i.e. statements produced by their target-language models). For native listeners, we do not confirm the tendency to mistrust non-native statements, but we do find a moderate correlation between the comprehensibility and credibility of foreign-accented utterances, giving limited support to the hypothesis that decreased perceptual fluency leads to decreased credibility.

The Interlanguage Speech Intelligibility Benefit as Bias Toward Native-Language Phonology.

Two hypotheses have been advanced in the recent literature with respect to the so-called Interlanguage Speech Intelligibility Benefit (ISIB): a nonnative speaker will be better understood by a another nonnative listener than a native speaker of the target language will be (a) only when the nonnatives share the same native language (matched interlanguage) or (b) even when the nonnatives have different mother tongues (non-matched interlanguage). Based on a survey of published experimental materials, the present article will demonstrate that both the restricted (a) and the generalized (b) hypotheses are false when the ISIB effect is evaluated in terms of absolute intelligibility scores. We will then propose a simple way to compute a relative measure for the ISIB (R-ISIB), which we claim is a more insightful way of evaluating the interlanguage benefit, and test the hypotheses in relative (R-ISIB) terms on the same literature data. We then find that our R-ISIB measure only supports the more restricted hypothesis (a) while rejecting the more general hypothesis (b). This finding shows that the native language shared by the interactants biases the listener toward interpreting sounds in terms of the phonology of the shared mother tongue.

Effects of listener factors and stimulus properties on the intelligibility, comprehensibility and accentedness of L2 speech

The intelligibility, comprehensibility and foreign accentedness of native and Polish-accented English sentences were evaluated by six Polish, six Spanish and six English speakers. The nonnative data were also analyzed for segmental and word stress errors. Results indicated that the three measures were partially independent of one another, supporting earlier findings that accented speech can be intelligible and comprehensible. An interlanguage speech intelligibility detriment was observed for Spanish listeners, but no clear evidence of an interlanguage speech intelligibility benefit was found, as nonnative listeners never outperformed native listeners. The number of segmental errors, rather than lexical stress errors, was found to correlate with comprehensibility and accentedness ratings of nonnative speech, but not with intelligibility scores. In general, the results point to a greater effect of stimulus properties than of listeners’ L1s in the perception of nonnative speech.

Listening with a foreign-accent: The interlanguage speech intelligibility benefit in Mandarin speakers of English

This study examined the intelligibility of native and Mandarin-accented English speech for native English and native Mandarin listeners. In the latter group, it also examined the role of the language environment and English proficiency. Three groups of listeners were tested: native English listeners (NE), Mandarin-speaking Chinese listeners in the US (M-US) and Mandarin listeners in Beijing, China (M-BJ). As a group, M-US and M-BJ listeners were matched on English proficiency and age of acquisition. A nonword transcription task was used. Identification accuracy for word-final stops in the nonwords established two independent interlanguage intelligibility effects. An interlanguage speech intelligibility benefit for listeners (ISIB-L) was manifest by both groups of Mandarin listeners outperforming native English listeners in identification of Mandarin-accented speech. In the benefit for talkers (ISIB-T), only M-BJ listeners were more accurate identifying Mandarin-accented speech than native English speech. Thus, both Mandarin groups demonstrated an ISIB-L while only the M-BJ group overall demonstrated an ISIB-T. The English proficiency of listeners was found to modulate the magnitude of the ISIB-T in both groups. Regression analyses also suggested that the listener groups differ in their use of acoustic information to identify voicing in stop consonants.

The matched and mismatched interlanguage speech intelligibility benefit for listeners (ISIB-L): Chinese L2 talkers’ production of English liquids

The matched and mismatched interlanguage speech intelligibility benefit for listeners (ISIB-L): Chinese L2 talkers’ production of English liquids

The Interlanguage Speech Intelligibility Benefit (ISIB) of English Prosody: The Case of Focal Prominence for Korean Learners of English and Natives

This study investigated the speech intelligibility of Korean-accented and native English focus speech for Korean and native English listeners. Three different types of focus in English, broad, narrow and contrastive, were naturally induced in semantically optimal dialogues. Seven high and seven low proficiency Korean speakers and seven native speakers participated in recording the stimuli with another native speaker. Fifteen listeners from each of Korean high & low proficiency and native groups judged audio signals of focus sentences. Results showed that Korean listeners were more accurate at identifying the focal prominence for Korean speakers' narrow focus speech than that of native speakers, and this suggests that the interlanguage speech intelligibility benefit-talker (ISIB-T) held true for narrow focus regardless of Korean speakers' and listeners' proficiency. However, Korean listeners did not outperform native listeners for Korean speakers' production of narrow focus, which did not support for the ISIB-listener (L). Broad and contrastive focus speech did not provide evidence for either the ISIB-T or ISIB-L. These findings are explained by the interlanguage shared by Korean speakers and listeners where they have established more L1-like common phonetic features and phonological representations. Once semantically and syntactically interpreted in a higher level processing in Korean narrow focus speech, the narrow focus was phonetically realized in a more intelligible way to Korean listeners due to the interlanguage. This may elicit ISIB. However, Korean speakers did not appear to make complete semantic/syntactic access to either broad or contrastive focus, which might lead to detrimental effects on lower level phonetic outputs in top-down processing. This is, therefore, attributed to the fact that Korean listeners did not take advantage over native listeners for Korean talkers and vice versa.

The role of first-language production accuracy and talker-listener alignment in second-language speech Intelligibility

This study investigated variability in L2 speech intelligibility as a function of L1 speech intelligibility and of talker-listener L1 match. Non-native Korean talkers varying in their L2 proficiency were recorded reading simple English (L2) and Korean (L1) sentences. The intelligibility of these sentences was then assessed by Korean listeners (both Korean and English productions) and English listeners (English productions only) in a sentence recognition task. The results revealed that for these Korean-English bilingual talkers, L1 intelligibility was significantly correlated with L2 intelligibility for both Korean and English listeners, suggesting that variability in L1 speech intelligibility can serve as a predictor of variability in L2 production accuracy. We also examined the interlanguage speech intelligibility benefit for non-native listeners (ISIB-L) (e.g., Bent & Bradlow, 2003; Hayes-Harb et al., 2008). Korean listeners performed better at identifying the sentences produced by Korean talkers with relatively low L2 intelligibility, implying that the benefit of a shared native language between talkers and listeners may be larger when non-native listeners process speech from a talker with low L2 intelligibility. Overall, these findings indicate that variability in L2 speech intelligibility is related to language-general talker characteristics as well as to the talker-listener language alignment.

The Interlanguage Speech Intelligibility Benefit for Korean Learners of English: Perception of English Front Vowels

ABSTRACTThe present work is a follow-up study to that of Han, Choi, Lim and Lee (2011), where an asymmetry in the source segments eliciting the interlanguage speech intelligibility benefit (ISIB) was found such that the vowels which did not match any vowel of the Korean language were likely to elicit more ISIB than matched vowels. In order to identify the source of the stronger ISIB in non-matched vowels, acoustic analyses of the stimuli were performed. Two pairs of English front vowels [i] vs. [ɪ], and [ɛ] vs. [ae] were recorded by English native talkers and two groups of Korean learners according to their English proficiency, and then their vowel duration and the frequencies of the first two formants (F1, F2) were measured. The results demonstrated that the non-matched vowels such as [ɪ], and [ae] produced by Korean talkers seemed to show more deviated acoustic characteristics from those of the natives, with longer duration and with closer formant values to the matched vowels, [i] and [ɛ], than those of the English natives. Combining the results of acoustic measurements in the present study and those of word identification in Han et al. (2011), we suggest that relatively better performance in word identification by Korean talkers/listeners than the native English talkers/listeners is associated with the shared interlanguage of Korean talkers and listeners. Key words: the interlanguage speech intelligibility benefit (ISIB), Korean front vowels

Production and perception of voicing and devoicing in similar German and English word pairs by native speakers of German

German manifests a phonological pattern of word-final consonant devoicing, with an underlying voicing contrast that is largely “neutralized” in speech, whereas English has a surface voicing contrast in final position. This raises questions concerning how well native German speakers learning English can produce a voicing contrast in English while continuing to neutralize the underlying German contrast, and especially how German speakers produce similar word pairs in the two languages (e.g., English: rod/rot; German: Rad/Rat). The present study examined the speech of 13 native Germans producing words in both languages and 13 native English speakers’ productions of English words. Acoustic analyses indicated that the native Germans showed more evidence of a final voicing distinction when producing English words than for phonologically similar German words. However, they typically produced fewer or less robust acoustic cues to word-final voicing when speaking English than the native English speakers did. An auditory word identification task also assessed intelligibility of German-accented and native English for German and English listeners. In contrast to studies showing an interlanguage speech intelligibility benefit, German listeners found native English speech to be more intelligible than German-accented English for the English word-final voicing contrast; they also did not find German-accented English more intelligible than native English listeners did.

The interlanguage speech intelligibility benefit for native speakers of Mandarin: Production and perception of English word-final voicing contrasts

This study investigated the intelligibility of native and Mandarin-accented English speech for native English and native Mandarin listeners. The word-final voicing contrast was considered (as in minimal pairs such as ‘cub’ and ‘cup’) in a forced-choice word identification task. For these particular talkers and listeners, there was evidence of an interlanguage speech intelligibility benefit for listeners (i.e., native Mandarin listeners were more accurate than native English listeners at identifying Mandarin-accented English words). However, there was no evidence of an interlanguage speech intelligibility benefit for talkers (i.e., native Mandarin listeners did not find Mandarin-accented English speech more intelligible than native English speech). When listener and talker phonological proficiency (operationalized as accentedness) was taken into account, it was found that the interlanguage speech intelligibility benefit for listeners held only for the low phonological proficiency listeners and low phonological proficiency speech. The intelligibility data were also considered in relation to various temporal-acoustic properties of native English and Mandarin-accented English speech in effort to better understand the properties of speech that may contribute to the interlanguage speech intelligibility benefit.

Relationships between the intelligibility and acoustic properties of native English and Mandarin-accented English

Studies examining effects of talkers’ and listeners’ linguistic backgrounds on speech intelligibility have produced mixed results, and relatively little is known about which acoustic-phonetic features of native and non-native speech are responsible for many findings. These issues are addressed here via investigation of how acoustic properties of final consonant voicing contrasts influence word intelligibility. Native English and native Mandarin talkers’ productions of English words were presented in isolation to native English and native Mandarin listeners in an identification task. Intelligibility findings were related to preceding vowel duration, stop consonant duration, burst duration, and proportion of voicing during stop closure. As expected, native English listeners were more accurate identifying words spoken by native than non-native talkers. In contrast to previous findings of an interlanguage speech intelligibility benefit (ISIB) for sentences, non-native listeners found native speech more intelligible than non-native speech. However, non-native listeners found non-native speech more intelligible than did native listeners. For native talkers, all four acoustic measures contributed significantly to correct identification of voicing contrasts by both native and non-native listeners (with closure voicing most salient). In contrast, for non-native talkers, listeners tended to rely primarily on closure voicing and burst duration. Ramifications for ISIB will be discussed.

Evidence against the mismatched interlanguage speech intelligibility benefit hypothesis

In a follow-up study to that of Bent and Bradlow (2003), carrier sentences containing familiar keywords were read aloud by five talkers (Korean high proficiency; Korean low proficiency; Saudi Arabian high proficiency; Saudi Arabian low proficiency; native English). The intelligibility of these keywords to 50 listeners in four first language groups (Korean, n = 10; Saudi Arabian, n = 10; native English, n = 10; other mixed first languages, n = 20) was measured in a word recognition test. In each case, the non-native listeners found the non-native low-proficiency talkers who did not share the same first language as the listeners the least intelligible, at statistically significant levels, while not finding the low-proficiency talker who shared their own first language similarly unintelligible. These findings indicate a mismatched interlanguage speech intelligibility detriment for low-proficiency non-native speakers and a potential intelligibility problem between mismatched first language low-proficiency speakers unfamiliar with each others' accents in English. There was no strong evidence to support either an intelligibility benefit for the high-proficiency non-native talkers to the listeners from a different first language background or to indicate that the native talkers were more intelligible than the high-proficiency non-native talkers to any of the listeners.

Perceptual and production variables in explicating interlanguage speech intelligibility benefit

This study attempts to investigate the importance of the degree of similarity or difference in the language backgrounds of the speakers and listeners, as it interacts differentially in intelligibility judgment of foreign-accented speech (Bent and Bradlow, 2003). The present study attempts to clarify the distinction in the matched and mismatched listening conditions, in context of addressing the overarching question whether auditory exposure to a language alone, without corresponding proficiency in production of that language, can provide a listening advantage. Particularly, do listeners understand accented-English speech spoken by native individuals of the language to which they are exposed to, as compared to listeners without that exposure? Greek-accented English speakers (and native monolingual English speakers) were judged for their speech intelligibility by four groups of listeners (n=10, each): native Greek speakers (matched), Greek-Americans (matched only through auditory exposure to Greek without any corresponding spoken proficiency), native monolingual American-English speakers (unmatched), and a mixed group (mismatched). Pilot data have shown that the intelligibility judgments by Greek-American listeners are intermediate to the native Greeks, and both the American-English and the mixed group. Further data-collection is underway, and will be presented as they bear important theoretical and clinical implications.