Language dominance and order of acquisition affect auditory translation priming in heritage speakers.

Late second language (L2) learners show translation priming from the first language (L1) to the second language (L1-L2), while L2-L1 effects are inconsistent. Late L2 learners also acquire the L2 after the L1 and are typically less dominant in the L2. As such, the relative contribution of language dominance and order of acquisition is confounded in these results. Here, Cantonese heritage and native speakers are tested in an auditory translation priming paradigm. As heritage speakers first learn Cantonese (L1) but later become dominant in English (L2), this profile allows for the potential dissociation of dominance and order of acquisition in translation priming. If order of acquisition is the primary factor, stronger priming is expected in the L1-L2 (Cantonese-English) direction; however, if dominance plays a stronger role, priming is expected in the L2-L1 (English-Cantonese) direction. Native speakers showed stronger L1-L2 priming, consistent with previous findings, while heritage speakers showed priming in both directions, and marginally larger L2-L1 priming. Treating language dominance as a continuous variable revealed that L1-L2 priming correlated with increased Cantonese dominance, while L2-L1 priming marginally correlated with increased English dominance. Collectively, these results suggest that both language dominance and order of acquisition help explain translation priming findings and bilingual lexical processing, generally. Overall, they invite a rethinking of the role of both variables in bilingual lexical access for speakers with different language dominance profiles.

Phonetic and Lexical Encoding of Tone in Cantonese Heritage Speakers.

Heritage speakers contend with at least two languages: the less dominant first language (L1), that is, the heritage language, and the more dominant second language (L2). In some cases, their L1 and L2 bear striking phonological differences. In the current study, we investigate Toronto-born Cantonese heritage speakers and their maintenance of Cantonese lexical tone, a linguistic feature that is absent from English, the more dominant L2. Across two experiments, Cantonese heritage speakers were tested on their phonetic/phonological and lexical encoding of tone in Cantonese. Experiment 1 was an AX discrimination task with varying inter-stimulus intervals (ISIs), which revealed that heritage speakers discriminated tone pairs with disparate pitch contours better than those with shared pitch contours. Experiment 2 was a medium-term repetition priming experiment, designed to extend the findings of Experiment 1 by examining tone representations at the lexical level. We observed a positive correlation between English dominance and priming in tone minimal pairs that shared contours. Thus, while increased English dominance does not affect heritage speakers' phonological-level representations, tasks that require lexical access suggest that heritage Cantonese speakers may not robustly and fully distinctively encode Cantonese tone in lexical memory.

Timing of brain entrainment to the speech envelope during speaking, listening and self-listening.

⁠This study investigates the dynamics of speech envelope tracking during speech production, listening and self-listening. We use a paradigm in which participants listen to natural speech (Listening), produce natural speech (Speech Production), and listen to the playback of their own speech (Self-Listening), all while their neural activity is recorded with EEG. After time-locking EEG data collection and auditory recording and playback, we used a Gaussian copula mutual information measure to estimate the relationship between information content in the EEG and auditory signals. In the 2-10 Hz frequency range, we identified different latencies for maximal speech envelope tracking during speech production and speech perception. Maximal speech tracking takes place approximately 110 ms after auditory presentation during perception and 25 ms before vocalisation during speech production. These results describe a specific timeline for speech tracking in speakers and listeners in line with the idea of a speech chain and hence, delays in communication.

Unified Coding of Spectral and Temporal Phonetic Cues: Electrophysiological Evidence for Abstract Phonological Features.

Spoken word recognition models and phonological theory propose that abstract features play a central role in speech processing. It remains unknown, however, whether auditory cortex encodes linguistic features in a manner beyond the phonetic properties of the speech sounds themselves. We took advantage of the fact that English phonology functionally codes stops and fricatives as voiced or voiceless with two distinct phonetic cues: Fricatives use a spectral cue, whereas stops use a temporal cue. Evidence that these cues can be grouped together would indicate the disjunctive coding of distinct phonetic cues into a functionally defined abstract phonological feature. In English, the voicing feature, which distinguishes the consonants [s] and [t] from [z] and [d], respectively, is hypothesized to be specified only for voiceless consonants (e.g., [s t]). Here, participants listened to syllables in a many-to-one oddball design, while their EEG was recorded. In one block, both voiceless stops and fricatives were the standards. In the other block, both voiced stops and fricatives were the standards. A critical design element was the presence of intercategory variation within the standards. Therefore, a many-to-one relationship, which is necessary to elicit an MMN, existed only if the stop and fricative standards were grouped together. In addition to the ERPs, event-related spectral power was also analyzed. Results showed an MMN effect in the voiceless standards block-an asymmetric MMN-in a time window consistent with processing in auditory cortex, as well as increased prestimulus beta-band oscillatory power to voiceless standards. These findings suggest that (i) there is an auditory memory trace of the standards based on the shared [voiceless] feature, which is only functionally defined; (ii) voiced consonants are underspecified; and (iii) features can serve as a basis for predictive processing. Taken together, these results point toward auditory cortex's ability to functionally code distinct phonetic cues together and suggest that abstract features can be used to parse the continuous acoustic signal.

Joint recording of EEG and audio signals in hyperscanning and pseudo-hyperscanning experiments.

Hyperscanning is an emerging technique that allows for the study of brain similarities between interacting individuals. This methodology has powerful implications for understanding the neural basis of joint actions, such as conversation; however, it also demands precise time-locking between the different brain recordings and sensory stimulation. Such precise timing, nevertheless, is often difficult to achieve. Recording auditory stimuli jointly with the ongoing high temporal resolution neurophysiological signal presents an effective way to control timing asynchronies offline between the digital trigger sent by the stimulation program and the actual onset of the auditory stimulus delivered to participants via speakers/headphones. This configuration is particularly challenging in hyperscanning setups due to the general increased complexity of the methodology. In other designs using the related technique of pseudo-hyperscanning, combined brain-auditory recordings are also a highly desirable feature, since reliable offline synchronization can be performed by using the shared audio signal. Here, we describe two hardware configurations wherein the real-time delivered auditory stimulus is recorded jointly with ongoing electroencephalographic (EEG) recordings. Specifically, we describe and provide customized implementations for joint EEG-audio recording in hyperscanning and pseudo-hyperscanning paradigms using hardware and software from Brain Products GmbH.•Joint EEG-audio recording configuration for hyperscanning and pseudo-hyperscanning paradigms.•Near zero-latency playback of auditory signal captured by a microphone.•Precise alignment between EEG and auditory stimulation.

Extracting Phonetic Features From Natural Classes: A Mismatch Negativity Study of Mandarin Chinese Retroflex Consonants.

How speech sounds are represented in the brain is not fully understood. The mismatch negativity (MMN) has proven to be a powerful tool in this regard. The MMN event-related potential is elicited by a deviant stimulus embedded within a series of repeating standard stimuli. Listeners construct auditory memory representations of these standards despite acoustic variability. In most designs that test speech sounds, however, this variation is typically intra-category: All standards belong to the same phonetic category. In the current paper, inter-category variation is presented in the standards. These standards vary in manner of articulation but share a common phonetic feature. In the standard retroflex experimental block, Mandarin Chinese speaking participants are presented with a series of "standard" consonants that share the feature [retroflex], interrupted by infrequent non-retroflex deviants. In the non-retroflex standard experimental block, non-retroflex standards are interrupted by infrequent retroflex deviants. The within-block MMN was calculated, as was the identity MMN (iMMN) to account for intrinsic differences in responses to the stimuli. We only observed a within-block MMN to the non-retroflex deviant embedded in the standard retroflex block. This suggests that listeners extract [retroflex] despite significant inter-category variation. In the non-retroflex standard block, because there is little on which to base a coherent auditory memory representation, no within-block MMN was observed. The iMMN to the retroflex was observed in a late time-window at centro-parieto-occipital electrode sites instead of fronto-central electrodes, where the MMN is typically observed, potentially reflecting the increased difficulty posed by the added variation in the standards. In short, participants can construct auditory memory representations despite significant acoustic and inter-category phonological variation so long as a shared phonetic feature binds them together.

Lexical bias in second language perception: Word position, age of arrival, and native language phonology.

The study examines whether non-native listeners leverage their L2 lexicon during a phonetic identification task and whether lexical bias is influenced by word position and length. Native English and native Mandarin speakers were tested on English words where the natural sibilant was replaced by one member of a nine-step [s]/[ʃ] continuum. English speakers experience a lexical bias effect for longer words. No clear bias was observed for Mandarin participants, although age of arrival correlated with amount of lexical bias but only in the initial position of longer words. These results suggest that language proficiency and higher-order linguistic representations drive perception.

A method for comparing perceptual distances and areas with multidimensional scaling.

This paper presents a method for adding additional statistical comparisons to multidimensional scaling (MDS). The object of study in our work is perceptual distances between speech sound categories. Typically, MDS solutions do not receive inferential statistical treatment and their visualizations present average results across numerous participants. This is problematic because it ignores inter-participant variation. To account for this variance, we have devised a simple technique for adding statistical power to the traditional MDS solution so that the distances between objects and the areas occupied by groups of objects can be compared more reliably than visual inspection of an MDS plot. We provide a method for comparing distances between two objects and for comparing the area of three or more objects. This method can be paired with varying statistical analysis to suit the researcher's needs. •Adds statistical power to multidimensional scaling.•Compares distances between segments.•Compares dispersion of groups of objects in multidimensional space.

Prediction of Agreement and Phonetic Overlap Shape Sublexical Identification.

The mapping between the physical speech signal and our internal representations is rarely straightforward. When faced with uncertainty, higher-order information is used to parse the signal and because of this, the lexicon and some aspects of sentential context have been shown to modulate the identification of ambiguous phonetic segments. Here, using a phoneme identification task (i.e., participants judged whether they heard [o] or [a] at the end of an adjective in a noun-adjective sequence), we asked whether grammatical gender cues influence phonetic identification and if this influence is shaped by the phonetic properties of the agreeing elements. In three experiments, we show that phrase-level gender agreement in Spanish affects the identification of ambiguous adjective-final vowels. Moreover, this effect is strongest when the phonetic characteristics of the element triggering agreement and the phonetic form of the agreeing element are identical. Our data are consistent with models wherein listeners generate specific predictions based on the interplay of underlying morphosyntactic knowledge and surface phonetic cues.

Linguistic category structure influences early auditory processing: Converging evidence from mismatch responses and cortical oscillations.

While previous research has established that language-specific knowledge influences early auditory processing, it is still controversial as to what aspects of speech sound representations determine early speech perception. Here, we propose that early processing primarily depends on information propagated top-down from abstractly represented speech sound categories. In particular, we assume that mid-vowels (as in 'bet') exert less top-down effects than the high-vowels (as in 'bit') because of their less specific (default) tongue height position as compared to either high- or low-vowels (as in 'bat'). We tested this assumption in a magnetoencephalography (MEG) study where we contrasted mid- and high-vowels, as well as the low- and high-vowels in a passive oddball paradigm. Overall, significant differences between deviants and standards indexed reliable mismatch negativity (MMN) responses between 200 and 300ms post-stimulus onset. MMN amplitudes differed in the mid/high-vowel contrasts and were significantly reduced when a mid-vowel standard was followed by a high-vowel deviant, extending previous findings. Furthermore, mid-vowel standards showed reduced oscillatory power in the pre-stimulus beta-frequency band (18-26Hz), compared to high-vowel standards. We take this as converging evidence for linguistic category structure to exert top-down influences on auditory processing. The findings are interpreted within the linguistic model of underspecification and the neuropsychological predictive coding framework.

Numbers are not like words: Different pathways for literacy and numeracy.

Literacy and numeracy are two fundamental cognitive skills that require mastering culturally-invented symbolic systems for representing spoken language and quantities. How numbers and words are processed in the human brain and their temporal dynamics remain unclear. Using MEG (magnetoencephalography), we find brain activation differences for literacy and numeracy from early stages of processing in the temporal-occipital and temporal-parietal regions. Native speakers of Spanish were exposed to visually presented words, pseudowords, strings of numbers, strings of letters and strings of symbols while engaged in a go/no-go task. Results showed more evoked neuromagnetic activity for words and pseudowords compared to symbols at ~120-130ms in the left occipito-temporal and temporal-parietal cortices (angular gyrus and intra-parietal sulcus) and at ~200ms in the left inferior frontal gyrus and left temporal areas. In contrast, numbers showed more activation than symbols at similar time windows in homologous regions of the right hemisphere: occipito-temporal and superior and middle temporal cortices at ~100-130ms. A direct comparison between the responses to words and numbers confirmed this distinct lateralization for the two stimulus types. These results suggest that literacy and numeracy follow distinct processing streams through the left and right hemispheres, respectively, and that the temporal-parietal and occipito-temporal regions may interact during processing alphanumeric stimuli.

Sensitivity to morphological composition in spoken word recognition: Evidence from grammatical and lexical identification tasks.

Access to morphological structure during lexical processing has been established across a number of languages; however, it remains unclear which constituents are held as mental representations in the lexicon. The present study examined the auditory recognition of different noun types across 2 experiments. The critical manipulations were morphological complexity and the presence of a verbal derivation or nominalizing suffix form. Results showed that nominalizations, such as "explosion," were harder to classify as a noun but easier to classify as a word when compared with monomorphemic words with similar actionlike semantics, such as "avalanche." These findings support the claim that listeners decompose morphologically complex words into their constituent units during processing. More specifically, the results suggest that people hold representations of base morphemes in the lexicon.

Asymmetries in the processing of vowel height.

PURPOSE: Speech perception can be described as the transformation of continuous acoustic information into discrete memory representations. Therefore, research on neural representations of speech sounds is particularly important for a better understanding of this transformation. Speech perception models make specific assumptions regarding the representation of mid vowels (e.g., [ε]) that are articulated with a neutral position in regard to height. One hypothesis is that their representation is less specific than the representation of vowels with a more specific position (e.g., [æ]). METHOD: In a magnetoencephalography study, we tested the underspecification of mid vowel in American English. Using a mismatch negativity (MMN) paradigm, mid and low lax vowels ([ε]/[æ]), and high and low lax vowels ([i]/[æ]), were opposed, and M100/N1 dipole source parameters as well as MMN latency and amplitude were examined. RESULTS: Larger MMNs occurred when the mid vowel [ε] was a deviant to the standard [æ], a result consistent with less specific representations for mid vowels. MMNs of equal magnitude were elicited in the high-low comparison, consistent with more specific representations for both high and low vowels. M100 dipole locations support early vowel categorization on the basis of linguistically relevant acoustic-phonetic features. CONCLUSION: We take our results to reflect an abstract long-term representation of vowels that do not include redundant specifications at very early stages of processing the speech signal. Moreover, the dipole locations indicate extraction of distinctive features and their mapping onto representationally faithful cortical locations (i.e., a feature map).

Evidence for early morphological decomposition: combining masked priming with magnetoencephalography.

Are words stored as morphologically structured representations? If so, when during word recognition are morphological pieces accessed? Recent masked priming studies support models that assume early decomposition of (potentially) morphologically complex words. The electrophysiological evidence, however, is inconsistent. We combined masked morphological priming with magneto-encephalography (MEG), a technique particularly adept at indexing processes involved in lexical access. The latency of an MEG component peaking, on average, 220 msec post-onset of the target in left occipito-temporal brain regions was found to be sensitive to the morphological prime-target relationship under masked priming conditions in a visual lexical decision task. Shorter latencies for related than unrelated conditions were observed both for semantically transparent (cleaner-CLEAN) and opaque (corner-CORN) prime-target pairs, but not for prime-target pairs with only an orthographic relationship (brothel-BROTH). These effects are likely to reflect a prelexical level of processing where form-based representations of stems and affixes are represented and are in contrast to models positing no morphological structure in lexical representations. Moreover, we present data regarding the transitional probability from stem to affix in a post hoc comparison, which suggests that this factor may modulate early morphological decomposition, particularly for opaque words. The timing of a robust MEG component sensitive to the morphological relatedness of prime-target pairs can be used to further understand the neural substrates and the time course of lexical processing.

You had me at "Hello": Rapid extraction of dialect information from spoken words.

Research on the neuronal underpinnings of speaker identity recognition has identified voice-selective areas in the human brain with evolutionary homologues in non-human primates who have comparable areas for processing species-specific calls. Most studies have focused on estimating the extent and location of these areas. In contrast, relatively few experiments have investigated the time-course of speaker identity, and in particular, dialect processing and identification by electro- or neuromagnetic means. We show here that dialect extraction occurs speaker-independently, pre-attentively and categorically. We used Standard American English and African-American English exemplars of 'Hello' in a magnetoencephalographic (MEG) Mismatch Negativity (MMN) experiment. The MMN as an automatic change detection response of the brain reflected dialect differences that were not entirely reducible to acoustic differences between the pronunciations of 'Hello'. Source analyses of the M100, an auditory evoked response to the vowels suggested additional processing in voice-selective areas whenever a dialect change was detected. These findings are not only relevant for the cognitive neuroscience of language, but also for the social sciences concerned with dialect and race perception.

Auditory Sensitivity to Formant Ratios:Toward an Account of Vowel Normalization.

A long-standing question in speech perception research is how do listeners extract linguistic content from a highly variable acoustic input. In the domain of vowel perception, formant ratios, or the calculation of relative bark differences between vowel formants, have been a sporadically proposed solution. We propose a novel formant ratio algorithm in which the first (F1) and second (F2) formants are compared against the third formant (F3). Results from two magnetoencephelographic (MEG) experiments are presented that suggest auditory cortex is sensitive to formant ratios. Our findings also demonstrate that the perceptual system shows heightened sensitivity to formant ratios for tokens located in more crowded regions of the vowel space. Additionally, we present statistical evidence that this algorithm eliminates speaker-dependent variation based on age and gender from vowel productions. We conclude that these results present an impetus to reconsider formant ratios as a legitimate mechanistic component in the solution to the problem of speaker normalization.

Neuromagnetic evidence for early auditory restoration of fundamental pitch.

BACKGROUND: Understanding the time course of how listeners reconstruct a missing fundamental component in an auditory stimulus remains elusive. We report MEG evidence that the missing fundamental component of a complex auditory stimulus is recovered in auditory cortex within 100 ms post stimulus onset. METHODOLOGY: Two outside tones of four-tone complex stimuli were held constant (1200 Hz and 2400 Hz), while two inside tones were systematically modulated (between 1300 Hz and 2300 Hz), such that the restored fundamental (also knows as "virtual pitch") changed from 100 Hz to 600 Hz. Constructing the auditory stimuli in this manner controls for a number of spectral properties known to modulate the neuromagnetic signal. The tone complex stimuli only diverged on the value of the missing fundamental component. PRINCIPAL FINDINGS: We compared the M100 latencies of these tone complexes to the M100 latencies elicited by their respective pure tone (spectral pitch) counterparts. The M100 latencies for the tone complexes matched their pure sinusoid counterparts, while also replicating the M100 temporal latency response curve found in previous studies. CONCLUSIONS: Our findings suggest that listeners are reconstructing the inferred pitch by roughly 100 ms after stimulus onset and are consistent with previous electrophysiological research suggesting that the inferential pitch is perceived in early auditory cortex.

Masked repetition priming using magnetoencephalography.

Masked priming is used in psycholinguistic studies to assess questions about lexical access and representation. We present two masked priming experiments using MEG. If the MEG signal elicited by words reflects specific aspects of lexical retrieval, then one expects to identify specific neural correlates of retrieval that are sensitive to priming. To date, the electrophysiological evidence has been equivocal. We report findings from two experiments. Both employed identity priming, where the prime and target are the same lexical item but differ in case (NEWS-news). The first experiment used only forward masking, while the prime in the second experiment was both preceded and followed by a mask (backward masking). In both studies, we find a significant behavioral effect of priming. Using MEG, we identified a component peaking approximately 225 ms post-onset of the target, whose latency was sensitive to repetition. These findings support the notion that properties of the MEG response index specific lexical processes and demonstrate that masked priming can be effectively combined with MEG to investigate the nature of lexical processing.