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Foreign-accented speech recognition is typically tested with linguistically simple materials, which offer a limited window into realistic speech processing. The present study examined the relationship between linguistic structure and talker intelligibility in several sentence-in-noise recognition experiments. Listeners transcribed simple/short and more complex/longer sentences embedded in noise. The sentences were spoken by three talkers of varying intelligibility: one native, one high-, and one low-intelligibility non-native English speakers. The effect of linguistic structure on sentence recognition accuracy was modulated by talker intelligibility. Accuracy was disadvantaged by increasing complexity only for the native and high intelligibility foreign-accented talkers, whereas no such effect was found for the low intelligibility foreign-accented talker. This pattern emerged across conditions: low and high signal-to-noise ratios, mixed and blocked stimulus presentation, and in the absence of a major cue to prosodic structure, the natural pitch contour of the sentences. Moreover, the pattern generalized to a different set of three talkers that matched the intelligibility of the original talkers. Taken together, the results in this study suggest that listeners employ qualitatively different speech processing strategies for low- versus high-intelligibility foreign-accented talkers, with sentence-related linguistic factors only emerging for speech over a threshold of intelligibility. Findings are discussed in the context of alternative accounts.

Memory for speech benefits from linguistic structure. Recall is better for sentences than for random strings of words (the “sentence superiority effect”; SSE), and evidence suggests that ongoing speech may be organized advantageously as clauses in memory (recall by word position shows within-clause U shape). In this study, we examined the SSE and clause-based organization for closed-set speech materials with low semantic predictability and without typical prosody. An overall SSE was observed and accuracy by word position was enhanced at the clause boundaries for these materials. Next, we tested the effects of mental manipulation on the SSE and clause-based organization. Listeners heard word strings that were syntactic, were arranged syntactically then presented backwards, or were random draws. Participants responded to materials as presented or in reversed order, requiring mental manipulation. Clause-level organization was apparent only for materials presented in syntactic order regardless of response order. After accounting for benefits due to reductions in uncertainty for these close-set materials, an SSE was present for syntactic materials regardless of response order, and for the syntactic backwards condition with reverse-order response (yielding a syntactically correct sentence in the response). Thus, the SSE was both resistant to and could be obtained following mental manipulation.

The current study investigated the phonetic adjustment mechanisms that underlie perceptual adaptation in first and second language (Dutch-English) listeners by exposing them to a novel English accent containing controlled deviations from the standard accent (e.g. /i/-to-/ɪ/ yielding /krɪm/ instead of /krim/ for ‘cream’). These deviations involved contrasts that either were contrastive or were not contrastive in Dutch. Following accent exposure with disambiguating feedback, listeners completed lexical decision and word identification tasks. Both native and second language listeners demonstrated adaptation, evidenced by higher lexical endorsement rates and word identification accuracy than untrained control listeners for items containing trained accent patterns. However, for L2 listeners, adaptation was modulated by the phonemic contrast, that is, whether or not it was contrastive in the listeners’ native language. Specifically, the training-induced criterion loosening for the L2 listeners was limited to contrasts that exist in both their L1, Dutch, and L2, English. For contrasts that are either absent or neutralized in Dutch, the L2 listeners demonstrated relatively loose pre-training criteria compared to L1 listeners. The results indicate that accent exposure induces both a general increase in tolerance for atypical speech input as well as targeted adjustments to specific categories for both L1 and L2 listeners.

Second-language (L2) speech is consistently slower than first-language (L1) speech, and L1 speaking rate varies within- and across-talkers depending on many individual, situational, linguistic, and sociolinguistic factors. It is asked whether speaking rate is also determined by a language-independent talker-specific trait such that, across a group of bilinguals, L1 speaking rate significantly predicts L2 speaking rate. Two measurements of speaking rate were automatically extracted from recordings of read and spontaneous speech by English monolinguals (n = 27) and bilinguals from ten L1 backgrounds (n = 86): speech rate (syllables/second), and articulation rate (syllables/second excluding silent pauses). Replicating prior work, L2 speaking rates were significantly slower than L1 speaking rates both across-groups (monolinguals' L1 English vs bilinguals' L2 English), and across L1 and L2 within bilinguals. Critically, within the bilingual group, L1 speaking rate significantly predicted L2 speaking rate, suggesting that a significant portion of inter-talker variation in L2 speech is derived from inter-talker variation in L1 speech, and that individual variability in L2 spoken language production may be best understood within the context of individual variability in L1 spoken language production.

Recordings of Spanish and English sentences by switched-dominance bilingual (SDB) Spanish (i.e., L2-dominant Spanish-English bilinguals) and by L1-dominant Spanish and English controls were presented to L1-dominant Spanish and English listeners, respectively. At –4 dB signal-to-noise ratio (SNR), Spanish and English productions by SDBs were equally intelligible with both reaching L1-dominant control levels. At –8 dB SNR, SDB English intelligibility matched that of L1-dominant English controls, yet SDB Spanish intelligibility was significantly lower than that of L1-dominant Spanish controls. These results emphasize that extended (but not early) exposure is both necessary and sufficient for robust speech learning.

Adaptation to foreign-accented sentences can be guided by knowledge of the lexical content of those sentences, which, being an exact match for the target, provides feedback on all linguistic levels. The extent to which this feedback needs to match the accented sentence was examined by manipulating the degree of match on different linguistic dimensions, including sub-lexical, lexical, and syntactic levels. Conditions where target-feedback sentence pairs matched and mismatched generated greater transcription improvement over non-English speech feedback, indicating listeners can draw upon sources of linguistic information beyond matching lexical items, such as sub- and supra-lexical information, during adaptation.

The present study provides evidence of a positive correlation between L1 and L2 intelligibility for bilingual talkers. Each talker in a group of Mandarin-English and Korean-English bilinguals was recorded producing simple sentences in each of their languages. The recordings were then presented to native listeners of the language-being-spoken in a test of sentence-in-noise recognition to yield a pair of L1 and L2 intelligibility scores for each talker based on the proportion of words correctly recognized. For all talkers, their L2 speech (i.e., Mandarin- or Korean-accented English) was consistently lower in intelligibility than their L1 speech (i.e., native accented Mandarin or Korean). This dissociation between L1-L2 speech intelligibility was evident in different intelligibility scores at comparable signal-to-noise ratios (as much as 35 percentage points for the Mandarin-English bilinguals) and in the required boost in signal-to-noise ratio to achieve comparable intelligibility (>8–10 dB). Critically, L1 and L2 intelligibility scores within the bilingual talkers were strongly positively correlated: Talkers with relatively high intelligibility in L1 also achieved relatively high intelligibility in L2. These results indicate a persistent influence of talker-specific trait characteristics that combine with, rather than are overwhelmed by, language-specific and dominance-dependent influences in bilingual speech production.

Language acquisition typically involves periods when the learner speaks and listens to the new language, and others when the learner is exposed to the language without consciously speaking or listening to it. Adaptation to variants of a native language occurs under similar conditions. Here, speech learning by adults was assessed following a training regimen that mimicked this common situation of language immersion without continuous active language processing. Experiment 1 focused on the acquisition of a novel phonetic category along the voice-onset-time continuum, while Experiment 2 focused on adaptation to foreign-accented speech. The critical training regimens of each experiment involved alternation between periods of practice with the task of phonetic classification (Experiment 1) or sentence recognition (Experiment 2) and periods of stimulus exposure without practice. These practice and exposure periods yielded little to no improvement separately, but alternation between them generated as much or more improvement as did practicing during every period. Practice appears to serve as a catalyst that enables stimulus exposures encountered both during and outside of the practice periods to contribute to quite distinct cases of speech learning. It follows that practice-plus-exposure combinations may tap a general learning mechanism that facilitates language acquisition and speech processing.

Prior research has demonstrated that listeners are sensitive to changes in the indexical (talker-specific) characteristics of speech input, suggesting that these signal-intrinsic features are integrally encoded in memory for spoken words. Given that listeners frequently must contend with concurrent environmental noise, to what extent do they also encode signal-extrinsic details? Native English listeners’ explicit memory for spoken English monosyllabic and disyllabic words was assessed as a function of consistency versus variation in the talker’s voice (talker condition) and background noise (noise condition) using a delayed recognition memory paradigm. The speech and noise signals were spectrally-separated, such that changes in a simultaneously presented non-speech signal (background noise) from exposure to test would not be accompanied by concomitant changes in the target speech signal. The results revealed that listeners can encode both signal-intrinsic talker and signal-extrinsic noise information into integrated cognitive representations, critically even when the two auditory streams are spectrally non-overlapping. However, the extent to which extra-linguistic episodic information is encoded alongside linguistic information appears to be modulated by syllabic characteristics, with specificity effects found only for monosyllabic items. These findings suggest that encoding and retrieval of episodic information during spoken word processing may be modulated by lexical characteristics.

This study examined the influence of background language variation on speech recognition. English listeners performed an English sentence recognition task in either “pure” background conditions in which all trials had either English or Dutch background babble or in mixed background conditions in which the background language varied across trials (i.e., a mix of English and Dutch or one of these background languages mixed with quiet trials). This design allowed the authors to compare performance on identical trials across pure and mixed conditions. The data reveal that speech-in-speech recognition is sensitive to contextual variation in terms of the target-background language (mis)match depending on the relative ease/difficulty of the test trials in relation to the surrounding trials.

Background: Masking release for an English sentence-recognition task in the presence of foreign-accented English speech compared with native-accented English speech was reported in Calandruccio et al (2010a). The masking release appeared to increase as the masker intelligibility decreased. However, it could not be ruled out that spectral differences between the speech maskers were influencing the significant differences observed. Purpose: The purpose of the current experiment was to minimize spectral differences between speech maskers to determine how various amounts of linguistic information within competing speech affect masking release. Research Design: A mixed-model design with within-subject (four two-talker speech maskers) and between-subject (listener group) factors was conducted. Speech maskers included native-accented English speech and high-intelligibility, moderate-intelligibility, and low-intelligibility Mandarin-accented English. Normalizing the long-term average speech spectra of the maskers to each other minimized spectral differences between the masker conditions. Study Sample: Three listener groups were tested, including monolingual English speakers with normal hearing, nonnative English speakers with normal hearing, and monolingual English speakers with hearing loss. The nonnative English speakers were from various native language backgrounds, not including Mandarin (or any other Chinese dialect). Listeners with hearing loss had symmetric mild sloping to moderate sensorineural hearing loss. Data Collection and Analysis: Listeners were asked to repeat back sentences that were presented in the presence of four different two-talker speech maskers. Responses were scored based on the key words within the sentences (100 key words per masker condition). A mixed-model regression analysis was used to analyze the difference in performance scores between the masker conditions and listener groups. Results: Monolingual English speakers with normal hearing benefited when the competing speech signal was foreign accented compared with native accented, allowing for improved speech recognition. Various levels of intelligibility across the foreign-accented speech maskers did not influence results. Neither the nonnative English-speaking listeners with normal hearing nor the monolingual English speakers with hearing loss benefited from masking release when the masker was changed from native-accented to foreign-accented English. Conclusions: Slight modifications between the target and the masker speech allowed monolingual English speakers with normal hearing to improve their recognition of native-accented English, even when the competing speech was highly intelligible. Further research is needed to determine which modifications within the competing speech signal caused the Mandarin-accented English to be less effective with respect to masking. Determining the influences within the competing speech that make it less effective as a masker or determining why monolingual normal-hearing listeners can take advantage of these differences could help improve speech recognition for those with hearing loss in the future.

I will describe the “progressive co-authorship cycle” as a strategy for promoting student publishing success. Crucial points in this progression are: (1) an initial phase in which the advisor is the lead author on a co-authored publication, (2) a middle phase in which the student and advisor are both in transition, and (3) a final phase in which the role reversal is complete and the student is the lead author on a co-authored publication. Each phase serves a unique purpose in the overall progression: modelling of good practice (phase 1), infusion of new energy and dynamism (phase 2), and finally, consolidation of a new and more equitable partnership (phase 3). I will emphasize that, as the fulcrum of the cycle, the middle phase is the most important yet easiest-to-neglect phase in a student-advisor relationship. During this phase, the student develops other co-authorship opportunities (e.g. with fellow students and/or other mentors). By infusing new ideas and research strategies into the mentor-mentee relationship, these “external” collaborations can be particularly enriching for phase 3. While this progression is rarely realized in clearly demarcated phases, it can provide a guiding framework for mentoring, and specifically for supporting student publishing success.I will describe the “progressive co-authorship cycle” as a strategy for promoting student publishing success. Crucial points in this progression are: (1) an initial phase in which the advisor is the lead author on a co-authored publication, (2) a middle phase in which the student and advisor are both in transition, and (3) a final phase in which the role reversal is complete and the student is the lead author on a co-authored publication. Each phase serves a unique purpose in the overall progression: modelling of good practice (phase 1), infusion of new energy and dynamism (phase 2), and finally, consolidation of a new and more equitable partnership (phase 3). I will emphasize that, as the fulcrum of the cycle, the middle phase is the most important yet easiest-to-neglect phase in a student-advisor relationship. During this phase, the student develops other co-authorship opportunities (e.g. with fellow students and/or other mentors). By infusing new ideas and research strategies into the mentor-mentee re...

Foreign-accented speech can be difficult to understand but listeners can adapt to novel talkers and accents with appropriate experience. Previous studies have demonstrated talker-independent but accent-dependent learning after training on multiple talkers from a single language background. Here, listeners instead were exposed to talkers from five language backgrounds during training. After training, listeners generalized their learning to novel talkers from language backgrounds both included and not included in the training set. These findings suggest that generalization of foreign-accent adaptation is the result of exposure to systematic variability in accented speech that is similar across talkers from multiple language backgrounds.

In this study, we consider how native status and signal degradation influence French listeners’ segmentation of an incoming speech stream containing liaison , a phonological process that misaligns word and syllable boundaries. In particular, we investigate how both first language (L1) and second language (L2) French listeners compensate for the syllable-word misalignment associated with liaison while segmenting French speech, and whether compensation-for-liaison strategies differ with decreasing signal-to-noise ratios. We consider the degree to which listeners rely on lexical knowledge, acoustic-phonetic cues, and distributional information to accomplish this compensation. Listeners completed a word identification task in which they heard adjective-noun sequences with or without liaison and were presented with the word or nonword alternatives for each noun that would result depending on whether the listener did or did not compensate for liaison. Results showed that both L1-French and L2-French listeners generally preferred lexically acceptable parses over those that resulted in a stranded nonword, and both groups gave significantly fewer lexically acceptable parses under harder listening conditions. However, the L2-French listeners demonstrated a pattern of boundary placement that indicated over-compensation for liaison, suggesting that they had successfully acquired, but not fully constrained, rules about liaison.

Children with dyslexia often exhibit increased variability in sensory and cognitive aspects of hearing relative to typically developing peers. Assistive listening devices (classroom FM systems) may reduce auditory processing variability by enhancing acoustic clarity and attention. We assessed the impact of classroom FM system use for 1 year on auditory neurophysiology and reading skills in children with dyslexia. FM system use reduced the variability of subcortical responses to sound, and this improvement was linked to concomitant increases in reading and phonological awareness. Moreover, response consistency before FM system use predicted gains in phonological awareness. A matched control group of children with dyslexia attending the same schools who did not use the FM system did not show these effects. Assistive listening devices can improve the neural representation of speech and impact reading-related skills by enhancing acoustic clarity and attention, reducing variability in auditory processing.

The goal of the present study was to devise a means of representing languages in a perceptual similarity space based on their overall phonetic similarity. In Experiment 1, native English listeners performed a free classification task in which they grouped 17 diverse languages based on their perceived phonetic similarity. A similarity matrix of the grouping patterns was then submitted to clustering and multidimensional scaling analyses. In Experiment 2, an independent group of native English listeners sorted the group of 17 languages in terms of their distance from English. Experiment 3 repeated Experiment 2 with four groups of non-native English listeners: Dutch, Mandarin, Turkish and Korean listeners. Taken together, the results of these three experiments represent a step towards establishing an approach to assess the overall phonetic similarity of languages. This approach could potentially provide the basis for developing predictions regarding foreign-accented speech intelligibility for various listener groups, and regarding speech perception accuracy in the context of background noise in various languages.

The bulk of the work on non-native speech has focused on average differences between L1 and L2 speakers. However there is growing evidence that variability also plays an important role in distinguishing L1 from L2 speech. While some studies have demonstrated greater variability for non-native than native speech (e.g., Baese-Berk & Morrill, 2015; Wade et al., 2007), others have demonstrated that under some circumstances non-native speech maybe lessvariable and that variability in non-native speech may shift as a function of many factors, including task (Baese-Berk & Morrill, to appear; Baese-Berk, Morrill, & Bradlow, 2016) and L1-L2 pairing (Vaughn, Baese-Berk, & Idemaru, to appear). In this study, we ask how variability manifests in L1 and L2 speech by speakers from a variety of language backgrounds. Specifically, we ask whether a speaker whose L1 speaking rate is highly variable is also highly variable in their L2. We also ask whether variability in speaking rate in L1 or L2 differs as a function of task (e.g., read vs. spontaneous speech) and complexity of the task (e.g., more or less complicated reading passages). The results of this study will inform our understanding of the myriad complex factors that influence non-native speech. The bulk of the work on non-native speech has focused on average differences between L1 and L2 speakers. However there is growing evidence that variability also plays an important role in distinguishing L1 from L2 speech. While some studies have demonstrated greater variability for non-native than native speech (e.g., Baese-Berk & Morrill, 2015; Wade et al., 2007), others have demonstrated that under some circumstances non-native speech maybe lessvariable and that variability in non-native speech may shift as a function of many factors, including task (Baese-Berk & Morrill, to appear; Baese-Berk, Morrill, & Bradlow, 2016) and L1-L2 pairing (Vaughn, Baese-Berk, & Idemaru, to appear). In this study, we ask how variability manifests in L1 and L2 speech by speakers from a variety of language backgrounds. Specifically, we ask whether a speaker whose L1 speaking rate is highly variable is also highly variable in their L2. We also ask whether variability in speaking rate in L1 or L2 differs as a function of tas...

How does linguistic knowledge influence speech production, perception, and learning? In this presentation, I will review three sources of empirical evidence for language specificity in some of the most basic processes of speech communication. Each line of evidence will highlight the contributions of the remarkable Jongman-Sereno collaboration—the honorees of this special session—and their continuing influence on generations of students. First, we will consider language specific phonetics as it relates to the acoustic details of speech categories across languages with different sound inventories, including Modern Greek, German, English, and Spanish. Second, we will examine the influence of language background on speech perception through comparisons of pitch perception by speakers of languages with and without lexical tone. Finally, we will focus on speech training in adults when presented with novel speech patterns, asking in particular how general learning principles interact with language-specificity for perceptual adaptation to second-language or foreign-accented speech. In each of these domains—production, perception, and learning—we will see the expanding circles of interaction amongst Jongman, Sereno, and their many students and colleagues. Critically, these Jongman-Sereno contributions underscore the importance of cross-language comparison coupled with a highly collaborative research approach for understanding speech processing and learning.

In adverse communicative contexts, speakers will modify their speech style to enhance intelligibility, which can involve a range of acoustic and articulatory adjustments. Prior work has focused on the influence of speaking style on spectral (e.g., vowel space expansion) and temporal distinctions (e.g., voice-onset time). Thus, this study investigated the extent to which such adjustments extend to the pitch dimension, namely lexical tone. Ten native Cantonese speakers were recorded producing five monosyllables with six Cantonese tones embedded in sentence contexts in both clear and conversational speaking styles. Acoustic analyses revealed that speakers produced two distinct styles, with longer vowel durations and greater vowel dispersion in clear relative to conversational speech. However, with regards to lexical tone production, the results indicated only a marginal re-adjustment of tones within the tone space as a result of clear speech. Specific contour tones, such as the low- and high-rising tones, saw increases in their F0 offset. However, mean F0, F0 range and tonal dispersion did not differ substantially between styles. These findings indicate that speakers maintain tonal stability across speaking styles, suggesting that, relative to segments, lexical tones may not be prioritized as phonological contrasts vital to enhance the overall intelligibility of the utterance.

Foreign-accented speech recognition is typically tested with linguistically simple sentences, which offer a limited window into speech processing. In this study, participants transcribed simple (i.e. mono-clausal, canonical declarative syntax) and complex (i.e. multi-clausal, non-canonical syntax, and/or passive voice) sentences in noise at two signal-to-noise ratios. The sentences were spoken by three talkers: one native, one high and one low intelligibility L2 English speaker. Unsurprisingly, recognition accuracy dropped with decreasing intelligibility and signal-to-noise ratio. Interestingly, accuracy dropped with increasing linguistic complexity only for the native and high intelligibility talkers. For the low intelligibility talker, sentence complexity did not affect recognition accuracy. This pattern of findings was present in mixed and blocked experimental designs, indicating no effect of familiarity with the talker. We argue that listeners employ qualitatively different speech processing strategies for low versus high intelligibility talkers, and suggest that this difference may be driven by the talker’s realization of prosodic structure. While native and high intelligibility talkers effectively encode the contrast between complex and simple sentences, low intelligibility talkers may not convey sufficient prosodic information, resulting in the recognition of both sentence types as non-hierarchically organized word sequences. [Work supported by Knowles Hearing Center, NIH grants R01-DC012289 and R01-DC005794.]

This article examines how probability (lexical frequency and previous mention), speech style, and prosody affect word duration, and how these factors interact. Participants read controlled materials in clear and plain speech styles. As expected, more probable words (higher frequencies and clear speech second mentions) were significantly shorter than less probable words, and lexical frequency words in plain speech were significantly shorter than those in clear speech. Interestingly, we found second mention reduction effects in both clear and second mention plain speech, indicating that while clear speech is hyper-articulated, this reduction hyper-articulation does not override probabilistic effects on duration. We also found an interaction between mention and frequency, but only in plain speech. High frequency words allowed more second mention reduction than low frequency words in plain speech, revealing a tendency to hypo-articulate as much as possible when all factors support it. Finally, we found that first mentions were more likely to be accented than second mentions. However, when these differences in accent likelihood were controlled, a significant second mention reduction effect remained. This supports the concept of a direct link between probability and duration, rather than a relationship solely mediated by prosodic prominence.

Most second language acquisition research focuses on linguistic structures, and less research has examined the acquisition of sociolinguistic patterns. The current study explored the perceptual classification of regional dialects of American English by native and non-native listeners using a free classification task. Results revealed similar classification strategies for the native and non-native listeners. However, the native listeners were more accurate overall than the non-native listeners. In addition, the non-native listeners were less able to make use of constellations of cues to accurately classify the talkers by dialect. However, the non-native listeners were able to attend to cues that were either phonologically or sociolinguistically relevant in their native language. These results suggest that non-native listeners can use information in the speech signal to classify talkers by regional dialect, but that their lack of signal-independent cultural knowledge about variation in the second language leads to less accurate classification performance.

This article provides an overview of the research concerning the nature of the distinct, listener-oriented speaking style called ‘clear speech’ and its effect on intelligibility for various listener populations. We review major findings that identify talker, listener and signal characteristics that contribute to the characteristically high intelligibility of clear speech. Understanding the interplay of these factors sheds light on the interaction between higher level cognitive and lower-level sensory and perceptual factors that affect language processing. Clear speech research is, thus, relevant for both its theoretical insights and practical applications. Throughout the review, we highlight open questions and promising future directions.

This study investigated the effect of hyperarticulated, intelligibility-enhancing clear speech on temporal characteristics as reflected in number, durations, and variability of consonant and vowel intervals in sentence- and paragraph-length utterances. The results of sentence-in-noise listening tests showed a consistent clear speech intelligibility gain across the utterances of varying complexity indicating that the talkers successfully maintained clear speech articulatory modifications throughout longer stretches of speech. The acoustic analysis revealed that some temporal restructuring accompanied changes in speaking style. This temporal restructuring was observed in the insertion of consonant and vowel segments that were dropped or coarticulated in conversational speech and in an increase in the number of prosodic phrases for clear speech. Importantly, coefficients of variation (variation of consonantal and vocalic intervals normalized for changes in speaking rate) for both consonantal and vowel intervals remained stable in the two speaking styles. Overall, these results suggest that increased intelligibility of clear speech may be attributed to prosodic structure enhancement (increased phrasing and enhanced segmentability) and stable global temporal properties.

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.

Objective Deficient prosody is a hallmark of the pragmatic (socially contextualized) language impairment in Autism Spectrum Disorders (ASD). Prosody communicates emotion and intention and is conveyed through acoustic cues such as pitch contour. Thus, the objective of this study was to examine the subcortical representations of prosodic speech in children with ASD. Methods Using passively evoked brainstem responses to speech syllables with descending and ascending pitch contours, we examined sensory encoding of pitch in children with ASD who had normal intelligence and hearing and were age-matched with typically developing (TD) control children. Results We found that some children on the autism spectrum show deficient pitch tracking (evidenced by increased Frequency and Slope Errors and reduced phase locking) compared with TD children. Conclusions This is the first demonstration of subcortical involvement in prosody encoding deficits in this population of children. Significance Our findings may have implications for diagnostic and remediation strategies in a subset of children with ASD and open up an avenue for future investigations.

This study investigated talker-dependent and talker-independent perceptual adaptation to foreign-accent English. Experiment 1 investigated talker-dependent adaptation by comparing native English listeners' recognition accuracy for Chinese-accented English across single and multiple talker presentation conditions. Results showed that the native listeners adapted to the foreign-accented speech over the course of the single talker presentation condition with some variation in the rate and extent of this adaptation depending on the baseline sentence intelligibility of the foreign-accented talker. Experiment 2 investigated talker-independent perceptual adaptation to Chinese-accented English by exposing native English listeners to Chinese-accented English and then testing their perception of English produced by a novel Chinese-accented talker. Results showed that, if exposed to multiple talkers of Chinese-accented English during training, native English listeners could achieve talker-independent adaptation to Chinese-accented English. Taken together, these findings provide evidence for highly flexible speech perception processes that can adapt to speech that deviates substantially from the pronunciation norms in the native talker community along multiple acoustic-phonetic dimensions.

Studies of speech perception in various types of background noise have shown that noise with linguistic content affects listeners differently than nonlinguistic noise [e.g., Simpson, S. A., and Cooke, M. (2005). “Consonant identification in N-talker babble is a nonmonotonic function of N,” J. Acoust. Soc. Am. 118, 2775–2778; Sperry, J. L., Wiley, T. L., and Chial, M. R. (1997). “Word recognition performance in various background competitors,” J. Am. Acad. Audiol. 8, 71–80] but few studies of multi-talker babble have employed background babble in languages other than the target speech language. To determine whether the adverse effect of background speech is due to the linguistic content or to the acoustic characteristics of the speech masker, this study assessed speech-in-noise recognition when the language of the background noise was either the same or different from the language of the target speech. Replicating previous findings, results showed poorer English sentence recognition by native English listeners in six-talker babble than in two-talker babble, regardless of the language of the babble. In addition, our results showed that in two-talker babble, native English listeners were more adversely affected by English babble than by Mandarin Chinese babble. These findings demonstrate informational masking on sentence-in-noise recognition in the form of “linguistic interference.” Whether this interference is at the lexical, sublexical, and/or prosodic levels of linguistic structure and whether it is modulated by the phonetic similarity between the target and noise languages remains to be determined.

Learning to read is a fundamental developmental milestone, and achieving reading competency has lifelong consequences. Although literacy development proceeds smoothly for many children, a subset struggle with this learning process, creating a need to identify reliable biomarkers of a child’s future literacy that could facilitate early diagnosis and access to crucial early interventions. Neural markers of reading skills have been identified in school-aged children and adults; many pertain to the precision of information processing in noise, but it is unknown whether these markers are present in pre-reading children. Here, in a series of experiments in 112 children (ages 3–14 y), we show brain–behavior relationships between the integrity of the neural coding of speech in noise and phonology. We harness these findings into a predictive model of preliteracy, revealing that a 30-min neurophysiological assessment predicts performance on multiple pre-reading tests and, one year later, predicts preschoolers’ performance across multiple domains of emergent literacy. This same neural coding model predicts literacy and diagnosis of a learning disability in school-aged children. These findings offer new insight into the biological constraints on preliteracy during early childhood, suggesting that neural processing of consonants in noise is fundamental for language and reading development. Pragmatically, these findings open doors to early identification of children at risk for language learning problems; this early identification may in turn facilitate access to early interventions that could prevent a life spent struggling to read., The neural coding of consonants in noise predicts early literacy skills in pre-reading children, providing a biological marker that may help to target early intervention., Author Summary Learning to read is a chief developmental milestone with lifelong consequences; although there are effective interventions for struggling readers, an ongoing challenge has been to identify candidates for intervention at a young-enough age. We measured the precision of the neural coding of consonants in noise, and found that pre-reading children (4 y old) with stronger neural processing had superior early literacy skills; one year later they were also stronger emerging readers. We applied the same neural coding measure to a cohort of older children: in addition to predicting these children’s literacy achievement, we could reliably predict which of the children had received a diagnosis of a reading impairment. Taken together, these results suggest that the neural coding of speech in noise plays a fundamental role in language development. Children who struggle to listen in noisy environments may struggle to make meaning of the language they hear on a daily basis, which can in turn set them at risk for literacy challenges. Evaluating the neural coding of speech in noise may provide an objective neurophysiological marker for these at-risk children, opening a door to early and specific interventions that may stave off a life spent struggling to read.

Early childhood is a critical period of auditory learning, during which children are constantly mapping sounds to meaning. But this auditory learning rarely occurs in ideal listening conditions—children are forced to listen against a relentless din. This background noise degrades the neural coding of these critical sounds, in turn interfering with auditory learning. Despite the importance of robust and reliable auditory processing during early childhood, little is known about the neurophysiology underlying speech processing in children so young. To better understand the physiological constraints these adverse listening scenarios impose on speech sound coding during early childhood, auditory-neurophysiological responses were elicited to a consonant-vowel syllable in quiet and background noise in a cohort of typically-developing preschoolers (ages 3–5 yr). Overall, responses were degraded in noise: they were smaller, less stable across trials, slower, and there was poorer coding of spectral content and the temporal envelope. These effects were exacerbated in response to the consonant transition relative to the vowel, suggesting that the neural coding of spectrotemporally-dynamic speech features is more tenuous in noise than the coding of static features—even in children this young. Neural coding of speech temporal fine structure, however, was more resilient to the addition of background noise than coding of temporal envelope information. Taken together, these results demonstrate that noise places a neurophysiological constraint on speech processing during early childhood by causing a breakdown in neural processing of speech acoustics. These results may explain why some listeners have inordinate difficulties understanding speech in noise. Speech-elicited auditory-neurophysiological responses offer objective insight into listening skills during early childhood by reflecting the integrity of neural coding in quiet and noise; this paper documents typical response properties in this age group. These normative metrics may be useful clinically to evaluate auditory processing difficulties during early childhood.

When instructed to speak clearly for people with hearing loss, a talker can effectively enhance the intelligibility of his/her speech by producing "clear" speech. We analyzed global acoustic properties of clear and conversational speech from two talkers and measured their speech intelligibility over a wide range of signal-to-noise ratios in acoustic and electric hearing. Consistent with previous studies, we found that clear speech had a slower overall rate, higher temporal amplitude modulations, and also produced higher intelligibility than conversational speech. To delineate the role of temporal amplitude modulations in clear speech, we extracted the temporal envelope from a number of frequency bands and replaced speech fine-structure with noise fine-structure to simulate cochlear implants. Although both simulated and actual cochlear-implant listeners required higher signal-to-noise ratios to achieve normal performance, a 3-4 dB difference in speech reception threshold was preserved between clear and conversational speech for all experimental conditions. These results suggest that while temporal fine structure is important for speech recognition in noise in general, the temporal envelope carries acoustic cues that contribute to the clear speech intelligibility advantage.

This study investigated how native language background influences the intelligibility of speech by non-native talkers for non-native listeners from either the same or a different native language background as the talker. Native talkers of Chinese (n = 2), Korean (n = 2), and English (n = 1) were recorded reading simple English sentences. Native listeners of English (n = 21), Chinese (n = 21), Korean (n = 10), and a mixed group from various native language backgrounds (n = 12) then performed a sentence recognition task with the recordings from the five talkers. Results showed that for native English listeners, the native English talker was most intelligible. However, for non-native listeners, speech from a relatively high proficiency non-native talker from the same native language background was as intelligible as speech from a native talker, giving rise to the "matched interlanguage speech intelligibility benefit." Furthermore, this interlanguage intelligibility benefit extended to the situation where the non-native talker and listeners came from different language backgrounds, giving rise to the "mismatched interlanguage speech intelligibility benefit." These findings shed light on the nature of the talker-listener interaction during speech communication.

Speech processing can often take place in adverse listening conditions that involve the mixing of speech and background noise. In this study, we investigated processing dependencies between background noise and indexical speech features, using a speeded classification paradigm (Garner, 1974; Exp. 1), and whether background noise is encoded and represented in memory for spoken words in a continuous recognition memory paradigm (Exp. 2). Whether or not the noise spectrally overlapped with the speech signal was also manipulated. The results of Experiment 1 indicated that background noise and indexical features of speech (gender, talker identity) cannot be completely segregated during processing, even when the two auditory streams are spectrally nonoverlapping. Perceptual interference was asymmetric, whereby irrelevant indexical feature variation in the speech signal slowed noise classification to a greater extent than irrelevant noise variation slowed speech classification. This asymmetry may stem from the fact that speech features have greater functional relevance to listeners, and are thus more difficult to selectively ignore than background noise. Experiment 2 revealed that a recognition cost for words embedded in different types of background noise on the first and second occurrences only emerged when the noise and the speech signal were spectrally overlapping. Together, these data suggest integral processing of speech and background noise, modulated by the level of processing and the spectral separation of the speech and noise.

This study examined whether language specific properties may lead to cross-language differences in the degree of phonetic reduction. Rates of syllabic reduction (defined here as reduction in which the number of syllables pronounced is less than expected based on canonical form) in English and Mandarin were compared. The rate of syllabic reduction was higher in Mandarin than English. Regardless of language, open syllables participated in reduction more often than closed syllables. The prevalence of open syllables was higher in Mandarin than English, and this phonotactic difference could account for Mandarin's higher rate of syllabic reduction.

In order to investigate the precise acoustic features of stop consonants that pose perceptual difficulties for some children with learning problems, discrimination thresholds along two separate synthetic /da-ga/ continua were compared in a group of children with learning problems (LP) and a group of normal children. The continua differed only in the duration of the formant transitions. Results showed that simply lengthening the formant transition duration from 40 to 80 ms did not result in improved discrimination thresholds for the LP group relative to the normal group. Consistent with previous findings, an electrophysiologic response that is known to reflect the brain's representation of a change from one auditory stimulus to another--the mismatch negativity (MMN)--indicated diminished responses in the LP group relative to the normal group to /da/ versus /ga/ when the transition duration was 40 ms. In the lengthened transition duration condition the MMN responses from the LP group were more similar to those from the normal group, and were enhanced relative to the short transition duration condition. These data suggest that extending the duration of the critical portion of the acoustic stimulus can result in enhanced encoding at a preattentive neural level; however, this stimulus manipulation on its own is not a sufficient acoustic enhancement to facilitate increased perceptual discrimination of this place-of-articulation contrast.

In order to gain insight into the interplay between the talker-, listener-, and item-related factors that influence speech perception, a large multi-talker database of digitally recorded spoken words was developed, and was then submitted to intelligibility tests with multiple listeners. Ten talkers produced two lists of words at three speaking rates. One list contained lexically "easy" words (words with few phonetically similar sounding "neighbors" with which they could be confused), and the other list contained lexically "hard" words (words with many phonetically similar sounding "neighbors"). An analysis of the intelligibility data obtained with native speakers of English (experiment 1) showed a strong effect of lexical similarity. Easy words had higher intelligibility scores than hard words. A strong effect of speaking rate was also found whereby slow and medium rate words had higher intelligibility scores than fast rate words. Finally, a relationship was also observed between the various stimulus factors whereby the perceptual difficulties imposed by one factor, such as a hard word spoken at a fast rate, could be overcome by the advantage gained through the listener's experience and familiarity with the speech of a particular talker. In experiment 2, the investigation was extended to another listener population, namely, non-native listeners. Results showed that the ability to take advantage of surface phonetic information, such as a consistent talker across items, is a perceptual skill that transfers easily from first to second language perception. However, non-native listeners had particular difficulty with lexically hard words even when familiarity with the items was controlled, suggesting that non-native word recognition may be compromised when fine phonetic discrimination at the segmental level is required. Taken together, the results of this study provide insight into the signal-dependent and signal-independent factors that influence spoken language processing in native and non-native listeners.

Purpose To investigate masking release for speech maskers for linguistically and phonetically close (English and Dutch) and distant (English and Mandarin) language pairs. Method Thirty-two monolingual speakers of English with normal audiometric thresholds participated in the study. Data are reported for an English sentence recognition task in English and for Dutch and Mandarin competing speech maskers (Experiment 1) and noise maskers (Experiment 2) that were matched either to the long-term average speech spectra or to the temporal modulations of the speech maskers from Experiment 1. Results Listener performance increased as the target-to-masker linguistic distance increased (English-in-English < English-in-Dutch < English-in-Mandarin). Conclusion Spectral differences between maskers can account for some, but not all, of the variation in performance between maskers; however, temporal differences did not seem to play a significant role.

This study explores phonetic convergence during conversations between pairs of talkers with varying language distance. Specifically, we examined conversations within two native English talkers and within two native Korean talkers who had either the same or different regional dialects, and between native and nonnative talkers of English. To measure phonetic convergence, an independent group of listeners judged the similarity of utterance samples from each talker through an XAB perception test, in which X was a sample of one talker's speech and A and B were samples from the other talker at either early or late portions of the conversation. The results showed greater convergence for same-dialect pairs than for either the different-dialect pairs or the different-L1 pairs. These results generally support the hypothesis that there is a relationship between phonetic convergence and interlocutor language distance. We interpret this pattern as suggesting that phonetic convergence between talker pairs that vary in the degree of their initial language alignment may be dynamically mediated by two parallel mechanisms: the need for intelligibility and the extra demands of nonnative speech production and perception.

This study investigated the encoding of spoken word attributes in a task of continuous recognition memory. In experiment 1, subjects were presented with a list of spoken words, and for each word they judged whether the word was ‘‘old’’ (had occurred previously in the list) or ‘‘new.’’ Results showed that subjects were more accurate at recognizing a word as ‘‘old’’ if it was repeated in the same voice (condition 1), and at the same rate of speech (condition 2); however, no recognition advantage was found for words repeated at the same amplitude (condition 3). In experiment 2, subjects gave an additional explicit judgment as to whether ‘‘old’’ words were repeated in the same voice (condition 1), rate (condition 2), or amplitude (condition 3). Subjects again showed a recognition advantage for words repeated in the same voice and rate, but no advantage occurred in the amplitude condition. However, subjects in all three conditions were significantly above chance accuracy in recognizing whether an ‘‘old’’ word ...

While the relationship of clear speaking style to intelligibility under challenging conditions has been established, it is a common observation that some speakers seem to be more intelligible than others for most listeners. In previous work, we have reported that automatic measures based on the technique of Landmark Detection appear to track differences between Clear and Conversational speaking style. One question that remains is whether Landmark measures can be used to predict which speakers are most likely to produce highly intelligible speech. In this study, we took advantage of a set of previously acquired databases to examine correlations between our Landmark-based measures and the Clear Speech productions of highly intelligible speech. Across these databases, we had data on intelligibility for a range of speakers. Results showed that speakers with high overall intelligibility in Clear Speech showed significantly different patterns on Landmark-based automatic measures, compared to speakers with more moderate performance on intelligibility measures. Applications of these results to problems in speech technology, linguistic education and clinical practice will be discussed.

Nonnative talkers tend to exhibit slower speech rates than native talkers at the group level. Here we ask whether individual variation in rate is language-general to the extent that L1 rate is a significant predictor of L2 rate within bilinguals. 62 nonnative English talkers participated in three speech production tasks in both their L1 (14 Cantonese, 14 Mandarin, 11 Korean, 4 Portuguese-Brazilian, 6 Spanish, 13 Turkish) and L2 (English), namely, reading a paragraph, spontaneously answering questions, and spontaneously describing a picture story. Two measurements of rate were automatically extracted from the recordings: speech rate (syllables per second), and articulation rate (syllables per second excluding silent pauses). As expected, L2 speech and articulation rates were overall slower than L1 speech and articulation rates for all tasks. Importantly, L2 speech rates and articulation rates were positively related to L1 speech rates and articulation rates, respectively. There were also significant differences in L2 speech rates and L2 articulation rates depending on L1 background and tasks. However, the positive relationship between L1 and L2 rates still holds with these other effects taken into consideration, suggesting that overall rate variation is partially an individual-specific property that transcends L1 and L2 within bilinguals.

Native and non-native speech differ in many ways, including overall speech rate, which tends to be substantially slower for non-native speakers (Guion et al., 2000). Recent work has suggested that non-native speech may be not only slower, but also more variable when non-natives are reading aloud (Baese-Berk and Morrill, 2015). Speaking rate also influences how listeners perceive non-native speech—slower readers are perceived as more accented and less comprehensible (Munro and Derwing, 1998). In the present study, we ask whether variability in speaking rate also has this effect on listeners. Specifically, we ask whether speaking rate variability is correlated with non-native speaker intelligibility and/or with judgments of fluency. In the present study, we ask listeners to transcribe sentences from speakers who show more or less variability in speaking rate across sentences in a paragraph-length reading passage. We also ask them to rate the fluency of the read sentences. Speech samples were taken from native Mandarin, Korean and English speakers’ recordings of the English “North Wind and the Sun” passage in the ALLSSTAR collection of digital speech recordings (Bradlow et al., 2010). These results provide insight into the relationships between variability, intelligibility, and fluency in both native and non-native speech.

This paper describes the development of the Wildcat Corpus of native- and foreign-accented English, a corpus containing scripted and spontaneous speech recordings from 24 native speakers of American English and 52 non-native speakers of English. The core element of this corpus is a set of spontaneous speech recordings, for which a new method of eliciting dialogue-based, laboratory-quality speech recordings was developed (the Diapix task). Dialogues between two native speakers of English, between two non-native speakers of English (with either shared or different L1s), and between one native and one non-native speaker of English are included and analyzed in terms of general measures of communicative efficiency. The overall finding was that pairs of native talkers were most efficient, followed by mixed native/non-native pairs and non-native pairs with shared L1. Non-native pairs with different L1s were least efficient. These results support the hypothesis that successful speech communication depends both on the alignment of talkers to the target language and on the alignment of talkers to one another in terms of native language background.

In this study, we compare the effects of English lexical features on word duration for native and non-native English speakers and for non-native speakers with different L1s and a range of L2 experience. We also examine whether non-native word durations lead to judgments of a stronger foreign accent. We measured word durations in English paragraphs read by 12 American English (AE), 20 Korean, and 20 Chinese speakers. We also had AE listeners rate the ‘accentedness’ of these non-native speakers. AE speech had shorter durations, greater within-speaker word duration variance, greater reduction of function words, and less between-speaker variance than non-native speech. However, both AE and non-native speakers showed sensitivity to lexical predictability by reducing second mentions and high-frequency words. Non-native speakers with more native-like word durations, greater within-speaker word duration variance, and greater function word reduction were perceived as less accented. Overall, these findings identify word duration as an important and complex feature of foreign-accented English.

It has been reported that listeners can benefit from a release in masking when the masker speech is spoken in a language that differs from the target speech compared to when the target and masker speech are spoken in the same language [Freyman, R. L. et al. (1999). J. Acoust. Soc. Am. 106, 3578–3588; Van Engen, K., and Bradlow, A. (2007), J. Acoust. Soc. Am. 121, 519–526]. It is unclear whether listeners benefit from this release in masking due to the lack of linguistic interference of the masker speech, from acoustic and phonetic differences between the target and masker languages, or a combination of these differences. In the following series of experiments, listeners’ sentence recognition was evaluated using speech and noise maskers that varied in the amount of linguistic content, including native-English, Mandarin-accented English, and Mandarin speech. Results from three experiments indicated that the majority of differences observed between the linguistic maskers could be explained by spectral differences between the masker conditions. However, when the recognition task increased in difficulty, i.e., at a more challenging signal-to-noise ratio, a greater decrease in performance was observed for the maskers with more linguistically relevant information than what could be explained by spectral differences alone.