Initial Phoneme Research Articles

Revealing the Dynamic Brain Connectivity from Perception of Speech Sound to Semantic Processing by EEG

Understanding brain processing mechanisms from the perception of speech sounds to high-level semantic processing is vital for effective human–robot communication. In this study, 128-channel electroencephalograph (EEG) signals were recorded when subjects were listening to real and pseudowords in Mandarin. By using an EEG source reconstruction method and a sliding-window Granger causality analysis, we analyzed the dynamic brain connectivity patterns. Results showed that the bilateral temporal cortex (lTC and rTC), the bilateral motor cortex (lMC and rMC), the frontal cortex (FC), and the occipital cortex (OC) were recruited in the process, with complex patterns in the real word condition than in the pseudoword condition. The spatial pattern is basically consistent with previous functional MRI studies on the understanding of spoken Chinese. For the real word condition, speech perception and processing involved different connection patterns in the initial phoneme perception and processing phase, the phonological processing and lexical selection phase, and the semantic integration phase. Specifically, compared with pseudowords, a hub region in the FC and unique patterns of lMC → rMC and lTC → FC connectivity were found during processing real words after 180 ms, while a distributed network of temporal, motor, and frontal brain areas was involved after 300 ms. This may be related to semantic processing and integration. The involvement of both bottom-up input and top-down modulation in real word processing may support the previously proposed TRACE model. In sum, the findings of this study suggest that representations of speech involve dynamic interactions among distributed brain regions that communicate through time-specific functional networks.

Subthalamic Nucleus and Sensorimotor Cortex Activity During Speech Production.

The sensorimotor cortex is somatotopically organized to represent the vocal tract articulators such as lips, tongue, larynx, and jaw. How speech and articulatory features are encoded at the subcortical level, however, remains largely unknown. We analyzed LFP recordings from the subthalamic nucleus (STN) and simultaneous electrocorticography recordings from the sensorimotor cortex of 11 human subjects (1 female) with Parkinson's disease during implantation of deep-brain stimulation (DBS) electrodes while they read aloud three-phoneme words. The initial phonemes involved either articulation primarily with the tongue (coronal consonants) or the lips (labial consonants). We observed significant increases in high-gamma (60-150 Hz) power in both the STN and the sensorimotor cortex that began before speech onset and persisted for the duration of speech articulation. As expected from previous reports, in the sensorimotor cortex, the primary articulators involved in the production of the initial consonants were topographically represented by high-gamma activity. We found that STN high-gamma activity also demonstrated specificity for the primary articulator, although no clear topography was observed. In general, subthalamic high-gamma activity varied along the ventral-dorsal trajectory of the electrodes, with greater high-gamma power recorded in the dorsal locations of the STN. Interestingly, the majority of significant articulator-discriminative activity in the STN occurred before that in sensorimotor cortex. These results demonstrate that articulator-specific speech information is contained within high-gamma activity of the STN, but with different spatial and temporal organization compared with similar information encoded in the sensorimotor cortex.SIGNIFICANCE STATEMENT Clinical and electrophysiological evidence suggest that the subthalamic nucleus (STN) is involved in speech; however, this important basal ganglia node is ignored in current models of speech production. We previously showed that STN neurons differentially encode early and late aspects of speech production, but no previous studies have examined subthalamic functional organization for speech articulators. Using simultaneous LFP recordings from the sensorimotor cortex and the STN in patients with Parkinson's disease undergoing deep-brain stimulation surgery, we discovered that STN high-gamma activity tracks speech production at the level of vocal tract articulators before the onset of vocalization and often before related cortical encoding.

Artikulacione i fonološke sposobnosti dece uzrasta od pet do sedam godina

The development of the child's speech sound articulation ability and phonological awareness goes through different stages during the child's preschool years. The aim of our research was to determine the articulation abilities and phonological awareness level in children with typical development. Our sample comprised 195 children aged five to seven. Speech sound articulation abilities and phonological awareness were assessed by means of the Global Test of Articulation and the FONT Phonological Awareness Test. The research results indicate that, depending on age, 42% to 78.3% of children are able to articulate clearly all 30 sounds of the Serbian language. An analysis of the Phonological Awareness Test results shows children performed best in the following tasks: syllable blending (99.1%), syllable segmentation (85%) and initial phoneme identification (86.1%), while they were least successful in the task of initial phoneme deletion (48.8%). Results have shown that children's success in most tasks within the framework of the elements of phonological awareness assessed - such as initial phoneme identification, rhyme recognition, phoneme segmentation, final phoneme identification, initial phoneme deletion and phoneme substitution (initial phoneme) - increases with children's age. The development of final phoneme identification, initial phoneme deletion and phoneme substitution (initial phoneme) abilities continues after children start school, as shown by data on the success rate among seven-year-olds. In view of the fact that phonological awareness plays an important role in the development and acquisition of reading ability, when working with preschool-age children particular attention should be devoted to tasks that stimulate the development of phonological awareness.

Fonološke sposobnosti dece predškolskog uzrasta

The aim of the research is to identify phonological abilities - voice analysis and word synthesis - and elements of phonological awareness in preschool children. The sample consisted of 85 children (42 boys and 43 girls), ages 6-7. The Test of the Speech Sound Analysis and Word Synthesis (Radičević & Marinković, 1993) was used to assess the ability of the speech sound analysis and synthesis, while the Test for Assessing Phonological Awareness - FONT Test (Subotić, 2011) was used to assess the respondents' phonological awareness. The results of the research showed that, in six out of eight tasks assessing the elements of phonological awareness, the children demonstrated an average and above average development of phonological abilities: syllable merging, syllabic segmentation, identifying the initial phoneme, identifying rhyme, phonemic segmentation, and identifying the final phoneme, while the lowest achievement was observed in the tasks of eliminating the initial phoneme and phonemic substitution of the initial phoneme. No statistically significant differences were found between boys and girls in their achievement on the FONT test tasks (p> 0.05). By further analyzing the results, and based on the results of average achievement, we found that the children constituting the research sample were more successful in the tasks of synthesizing monosyllabic and two-syllable words, than in the analysis of monosyllabic and two-syllable words. Differences in achievement between boys and girls regarding the speech sound analysis and synthesis tasks were identified in the tasks involving the speech sound synthesis (p <0.05).

Balancing Prediction and Sensory Input in Speech Comprehension: The Spatiotemporal Dynamics of Word Recognition in Context.

Spoken word recognition in context is remarkably fast and accurate, with recognition times of ∼200 ms, typically well before the end of the word. The neurocomputational mechanisms underlying these contextual effects are still poorly understood. This study combines source-localized electroencephalographic and magnetoencephalographic (EMEG) measures of real-time brain activity with multivariate representational similarity analysis to determine directly the timing and computational content of the processes evoked as spoken words are heard in context, and to evaluate the respective roles of bottom-up and predictive processing mechanisms in the integration of sensory and contextual constraints. Male and female human participants heard simple (modifier-noun) English phrases that varied in the degree of semantic constraint that the modifier (W1) exerted on the noun (W2), as in pairs, such as "yellow banana." We used gating tasks to generate estimates of the probabilistic predictions generated by these constraints as well as measures of their interaction with the bottom-up perceptual input for W2. Representation similarity analysis models of these measures were tested against electroencephalographic and magnetoencephalographic brain data across a bilateral fronto-temporo-parietal language network. Consistent with probabilistic predictive processing accounts, we found early activation of semantic constraints in frontal cortex (LBA45) as W1 was heard. The effects of these constraints (at 100 ms after W2 onset in left middle temporal gyrus and at 140 ms in left Heschl's gyrus) were only detectable, however, after the initial phonemes of W2 had been heard. Within an overall predictive processing framework, bottom-up sensory inputs are still required to achieve early and robust spoken word recognition in context.SIGNIFICANCE STATEMENT Human listeners recognize spoken words in natural speech contexts with remarkable speed and accuracy, often identifying a word well before all of it has been heard. In this study, we investigate the brain systems that support this important capacity, using neuroimaging techniques that can track real-time brain activity during speech comprehension. This makes it possible to locate the brain areas that generate predictions about upcoming words and to show how these expectations are integrated with the evidence provided by the speech being heard. We use the timing and localization of these effects to provide the most specific account to date of how the brain achieves an optimal balance between prediction and sensory input in the interpretation of spoken language.

Neural activity reveals effects of aging on inhibitory processes during word retrieval

ABSTRACTWord retrieval difficulties are one of the most frustrating problems for older adults. Poorer access to phonological representation of the target word has been postulated as the underlying deficit, supported by findings of improved word retrieval after phonological priming. To better understand aging effects in the underlying neurophysiology associated with word retrieval, this study examined electrophysiological correlates of phonological priming and word retrieval in adults. Young, middle-aged, and older adults viewed pictures that were preceded by pseudo-word primes that either shared initial phonemes with or were unrelated to the picture’s name. Participants made phonological judgments regarding the prime and picture prior to naming the picture. Behavioral and event-related potential correlates of phonological priming and word retrieval were recorded. All groups benefitted similarly from phonological priming, evidenced by faster phonological judgment response times and increased ease of word retrieval for primed pictures, indexed by the N400 priming effect. The peak latency of the N2, however, showed an incremental delay with age. High correlation between N2 peak latency and clinical measures of inhibition suggested an age-related delay in the inhibition of primed lexical competitors. Taken together, our results indicated intact activation of phonological representation of the picture’s name but age-related delays in inhibition of primed competitors. Interestingly, our findings revealed that delays in inhibiting lexical competitors may begin as early as middle age, highlighting the importance of including multiple age groups to better represent the aging trajectory.

Contributions of the Components of Phonemic Awareness to Letter-Sound Knowledge With Kindergarten Students in High-Poverty Urban Elementary Schools

Phonemic awareness (PA) includes rhyming, phoneme isolation, blending, and segmenting, but the relative importance of each component is unclear, especially for students from high-poverty areas. The current study examined the relationship between components of PA and an early literacy measure among 192 kindergarten students from high-poverty urban elementary schools. A researcher assessed the students using the Quick Phonemic Awareness Assessment and a measure of letter-sound knowledge (LSK). The results showed that PA was highly correlated with LSK. Initial phoneme isolation, blending, and segmenting contributed significant variance to LSK, but rhyming did not. The data supported the Quick Phonemic Awareness Assessment as a measure of PA among an urban population but questioned the importance of rhyming as a predictive component of PA.

Theta oscillations mediate pre-activation of highly expected word initial phonemes

Prediction has been proposed to be a fundamental neurocognitive mechanism. However, its role in language comprehension is currently under debate. In this magnetoencephalography study we aimed to find evidence of word-form phonological pre-activation and to characterize the oscillatory mechanisms supporting this. Participants were presented firstly with a picture of an object, and then, after a delay (fixed or variable), they heard the corresponding word. Target words could contain a phoneme substitution, and participants’ task was to detect mispronunciations. Word-initial phonemes were either fricatives or plosives, generating two experimental conditions (expect-fricative and expect-plosive). In the pre-word interval, significant differences (α = 0.05) emerged between conditions both for fixed and variable delays. Source reconstruction of this effect showed a brain-wide network involving several frequency bands, including bilateral superior temporal areas commonly associated with phonological processing, in a theta range. These results show that phonological representations supported by the theta band may be active before word onset, even under temporal uncertainty. However, in the evoked response just prior to the word, differences between conditions were apparent under variable- but not fixed-delays. This suggests that additional top-down mechanisms sensitive to phonological form may be recruited when there is uncertainty in the signal.

Eyetracking of coarticulatory cue responses in children and adults

ABSTRACT Prior work suggests listeners are sensitive to coarticulatory cues during spoken word recognition; however, little is known about how this ability develops in children. In the present study, children and adults listened to words containing congruent and incongruent coarticulatory cues while looking at a two-picture display. We manipulated the congruency of the auditory-coarticulatory information such that the initial phoneme of the auditory cue matched the target, or contained an incongruent initial phoneme that instead matched the distractor picture. Accordingly, we observed both slower rates of looks to the target and higher rates of looks to the distractor on incongruent trials, indicating that both children and adults were sensitive to coarticulatory congruency. These findings suggest that children maintain detailed phonological representations of words, and may use coarticulatory information to facilitate spoken word recognition.

Letter sound characters and imaginary narratives: Can they enhance motivation and letter sound learning?

A total of thirty-eight preschool children were randomly assigned to one of two explicit teaching treatments to teach alphabet letter sounds. One treatment was designed to enhance motivation and learning by utilizing letters with letter sound characters integrated into the letter shapes (integrated mnemonics) and short narratives about the letter sound characters. In the treated control, plain letters and alphabet books were the foundation of instruction. There were no significant treatment effects on children’s perceptions of ability or desire/interest for school tasks (cross-domain) or letters (domain-specific). Children’s motivation increased significantly from pretest to posttest on three of four motivation measures including interest/desire for letters (domain-specific), and interest/desire and ability perceptions for school tasks (cross-domain). Effect sizes were dz=0.50, dz=0.34, and dz=0.40, respectively. There were significant treatment effects in favor of integrated mnemonics on identifying letter sounds, identifying initial consonants, and blending. Treatment effect sizes were d=1.31 for letter sounds, d=0.61 for initial phoneme identification (ID), and d=0.62 for blending phonemes. Self-reports of ability and desire/interest for school tasks and letters were correlated with learning. Results are interpreted as suggesting that (a) identifying features of instruction that enhance motivation may require stronger instructional elements, increased alignment between features of instruction and measures, and improved measures, (b) small differences in the nature of letter sound instruction matter for learning with superiority for instruction including letter characters integrated into letter forms and imaginary narratives, and (c) relationships among motivation, learning, and instruction are discernible in preschool children.

Delayed silent phoneme monitoring in adults who do and do not stutter

ABSTRACT Previous research employed silent phoneme monitoring tasks to examine differences in phonological encoding in adults who stutter (AWS) compared to adults who do not stutter (AWNS). The primary purpose of this study was to apply a modified version of the task – the delayed silent phoneme monitoring task – to examine the integrity of the phonological speech plan within working memory in AWS and AWNS before and after subvocal rehearsal. The secondary purpose of this study was to examine whether group differences were more apparent when greater phonological demand was placed upon phonological working memory. In Experiment 1, 20 adults (10 AWNS, 10 AWS) identified target phonemes within trochaic nonwords held in memory before the initiation of subvocal rehearsal (1 s) and after subvocal rehearsal (4 s). In Experiment 2, an additional 20 adults (10 AWNS, 10 AWS) monitored identical nonwords with low-frequency iambic stress. Speed and accuracy of manual response was measured, as well as post-trial verbal productions. Both groups identified the initial phoneme of trochaic stimuli fastest, irrespective of stress, and both groups monitored phonemes faster after the 4 s delay. However, AWS identified phonemes within iambic stimuli with less accuracy than AWNS. Group differences in monitoring errors were most evident for phonemes immediately following syllable boundary, and after subvocal rehearsal. Preliminary findings suggest AWS may exhibit distinct difficulties relative to AWNS when accessing segmental information after subvocal rehearsal is required, but only when target words are more phonologically demanding (i.e., low-frequency iambic stress).

The influence of the native language on phonological preparation in spoken word production in a second language

Abstract Three experiments investigated the phonological preparation unit in planning English spoken words, comparing English monolinguals, native Chinese and Japanese-speakers who spoke English as their second language. All three groups named pictures in English, and the names could either share the same initial phoneme, mora, or syllable, or had no systematic commonality. A phoneme preparation effect was shown among English monolinguals but not among the two bilingual groups, suggesting that the phoneme is the phonological preparation unit for English monolinguals, but not for the two bilingual groups. All three groups showed mora and syllable preparation effects, but further analysis and a follow-up experiment suggested that Chinese-English bilinguals may treat morae as open syllables. English monolinguals showed similar phoneme and mora preparation effect sizes, possibly as a result of flexibility. Together, the selection of phonological preparation could be flexible, influenced by both the nature of the target language and speakers’ language experiences.

Use of a phoneme monitoring task to examine lexical access in adults who do and do not stutter

Previous work has postulated that a deficit in lexicalization may be an underlying cause of a stuttering disorder (Prins, Main, & Wampler, 1997; Wingate, 1988). This study investigates the time course of lexicalization of nouns and verbs in adults who stutter. A generalized phoneme monitoring (PM) paradigm was used. Adults who stutter (AWS) and typically-fluent peers both showed an expected effect of word class (verbs yielded slower and less accurate monitoring than nouns), as well as phoneme position (word medial/final phonemes yielded slower and less accurate monitoring than word initial phonemes). However, AWS had considerably more difficulty when targets to be monitored were embedded in the medial position. A negative correlation between speed and accuracy was found in typically fluent adults, but not in AWS. AWS also scored nonsignificantly more poorly on an experimental language task. Because of the additional difficulty noted in AWS with word-medial targets, our results provide evidence of phonological encoding differences between the two groups. Expanded use of the PM paradigm is recommended for the exploration of additional aspects of language processing in people who stutter.

The asymmetric contribution of consonants and vowels to phonological similarity

Abstract Lexical priming is known to arise from phonological similarity between prime and target, and this phenomenon is an important component of our understanding of the processes of lexical access and competition. However, the precise nature of the role of phonological similarity in lexical priming is understudied. In the present study, two experiments were conducted in which participants performed auditory lexical decision on CVC targets which were preceded by primes that either matched the target in all phonemes (CVC condition), in the first two phonemes (CV_ condition), the last two phonemes (_VC condition), the initial and last phonemes (C_C condition) or no phonemes (unrelated condition). Relative to the unrelated condition, all conditions except CV_ led to facilitation of response time to target words. The _VC and C_C conditions led to equivalent facilitation magnitude, while the CV_ condition showed neither facilitation nor inhibition. Accounting for these results requires appeal to processes of lexical competition and also to the notion that phonemes do not lend equivalent phonological similarity; that is, vowels and consonants are processed differently.

Priming production: Neural evidence for enhanced automatic semantic activity preceding language production in schizophrenia.

IntroductionLexico-semantic disturbances are considered central to schizophrenia. Clinically, their clearest manifestation is in language production. However, most studies probing their underlying mechanisms have used comprehension or categorization tasks. Here, we probed automatic semantic activity prior to language production in schizophrenia using event-related potentials (ERPs).Methods19 people with schizophrenia and 16 demographically-matched healthy controls named target pictures that were very quickly preceded by masked prime words. To probe automatic semantic activity prior to production, we measured the N400 ERP component evoked by these targets. To determine the origin of any automatic semantic abnormalities, we manipulated the type of relationship between prime and target such that they overlapped in (a) their semantic features (semantically related, e.g. “cake” preceding a < picture of a pie >, (b) their initial phonemes (phonemically related, e.g. “stomach” preceding a < picture of a starfish >), or (c) both their semantic features and their orthographic/phonological word form (identity related, e.g. “socks” preceding a < picture of socks >). For each of these three types of relationship, the same targets were paired with unrelated prime words (counterbalanced across lists). We contrasted ERPs and naming times to each type of related target with its corresponding unrelated target.ResultsPeople with schizophrenia showed abnormal N400 modulation prior to naming identity related (versus unrelated) targets: whereas healthy control participants produced a smaller amplitude N400 to identity related than unrelated targets, patients showed the opposite pattern, producing a larger N400 to identity related than unrelated targets. This abnormality was specific to the identity related targets. Just like healthy control participants, people with schizophrenia produced a smaller N400 to semantically related than to unrelated targets, and showed no difference in the N400 evoked by phonemically related and unrelated targets. There were no differences between the two groups in the pattern of naming times across conditions.ConclusionPeople with schizophrenia can show abnormal neural activity associated with automatic semantic processing prior to language production. The specificity of this abnormality to the identity related targets suggests that that, rather than arising from abnormalities of either semantic features or lexical form alone, it may stem from disruptions of mappings (connections) between the meaning of words and their form.

Less is more: neural mechanisms underlying anomia treatment in chronic aphasic patients.

See Thompson and Woollams (doi:10.1093/brain/awx264) for a scientific commentary on this article. Previous research with aphasic patients has shown that picture naming can be facilitated by concurrent phonemic cueing [e.g. initial phoneme(s) of the word that the patient is trying to retrieve], both as an immediate word retrieval technique, and when practiced repeatedly over time as a long-term anomia treatment. Here, to investigate the neural mechanisms supporting word retrieval, we adopted—for the first time—a functional magnetic resonance imaging task using the same naming procedure as it occurs during the anomia treatment process. Before and directly after a 6-week anomia treatment programme, 18 chronic aphasic stroke patients completed our functional magnetic resonance imaging protocol—a picture naming task aided by three different types of phonemic cues (whole words, initial phonemes, final phonemes) and a noise-control condition. Patients completed a naming task based on the training materials, and a more general comprehensive battery of language tests both before and after the anomia treatment, to determine the effectiveness and specificity of the therapy. Our results demonstrate that the anomia treatment was effective and specific to speech production, significantly improving both patients’ naming accuracy and reaction time immediately post-treatment (unstandardized effect size: 29% and 17%, respectively; Cohen’s d: 3.45 and 1.83). Longer term gains in naming were maintained 3 months later. Functional imaging results showed that both immediate and long-term facilitation of naming involved a largely overlapping bilateral frontal network including the right anterior insula, inferior frontal and dorsal anterior cingulate cortices, and the left premotor cortex. These areas were associated with a neural priming effect (i.e. reduced blood oxygen level-dependent signal) during both immediate (phonemically-cued versus control-cue conditions), and long-term facilitation of naming (i.e. treated versus untreated items). Of note is that different brain regions were sensitive to different phonemic cue types. Processing of whole word cues was associated with increased activity in the right angular gyrus; whereas partial word cues (initial and final phonemes) recruited the left supplementary motor area, and right anterior insula, inferior frontal cortex, and basal ganglia. The recruitment of multiple and bilateral areas may help explain why phonemic cueing is such a successful behavioural facilitation tool for anomia treatment. Our results have important implications for optimizing current anomia treatment approaches, developing new treatments, and improving speech outcome for aphasic patients.

The cortical dynamics of speaking: Lexical and phonological knowledge simultaneously recruit the frontal and temporal cortex within 200 ms

Language production models typically assume that retrieving a word for articulation is a sequential process with substantial functional delays between conceptual, lexical, phonological and motor processing, respectively. Nevertheless, explicit evidence contrasting the spatiotemporal dynamics between different word production components is scarce. Here, using anatomically constrained magnetoencephalography during overt meaningful speech production, we explore the speed with which lexico-semantic versus acoustic-articulatory information of a to-be-uttered word become first neurophysiologically manifest in the cerebral cortex. We demonstrate early modulations of brain activity by the lexical frequency of a word in the temporal cortex and the left inferior frontal gyrus, simultaneously with activity in the motor and the posterior superior temporal cortex reflecting articulatory-acoustic phonological features (+LABIAL vs. +CORONAL) of the word-initial speech sounds (e.g., Monkey vs. Donkey). The specific nature of the spatiotemporal pattern correlating with a word's frequency and initial phoneme demonstrates that, in the course of speech planning, lexico-semantic and phonological-articulatory processes emerge together rapidly, drawing in parallel on temporal and frontal cortex. This novel finding calls for revisions of current brain language theories of word production.

Semantic and Phonological Encoding in Adults Who Stutter: Silent Responses to Pictorial Stimuli.

Research on language planning in adult stuttering is relatively sparse and offers diverging arguments about a potential causative relationship between semantic and phonological encoding and fluency breakdowns. This study further investigated semantic and phonological encoding efficiency in adults who stutter (AWS) by means of silent category and phoneme identification, respectively. Fifteen AWS and 15 age- and sex-matched adults who do not stutter (ANS) participated. The groups were compared on the basis of the accuracy and speed of superordinate category (animal vs. object) and initial phoneme (vowel vs. consonant) decisions, which were indicated manually during silent viewing of pictorial stimuli. Movement execution latency was accounted for, and no other cognitive, linguistic, or motor demands were posed on participants' responses. Therefore, category identification accuracy and speed were considered indirect measures of semantic encoding efficiency and phoneme identification accuracy and speed of phonological encoding efficiency. For category decisions, AWS were slower but not less accurate than ANS, with objects eliciting more errors and slower responses than animals in both groups. For phoneme decisions, the groups did not differ in accuracy, with consonant errors outnumbering vowel errors in both groups, and AWS were slower than ANS in consonant but not vowel identification, with consonant response time lagging behind vowel response time in AWS only. AWS were less efficient than ANS in semantic encoding, and they might harbor a consonant-specific phonological encoding weakness. Future independent studies are warranted to discover if these positive findings are replicable and a marker for persistent stuttering.

Effect of voicing on perceptual auditory laterality in Estonian and Norwegian native speakers

ABSTRACTAs a reliable and valid measures of perceptual auditory laterality, dichotic listening has been successfully applied in studies in many countries and languages. However, languages differ in the linguistic relevance of change in initial phoneme of words (e.g., for word identification). In the present cross-language study, we examine the effect of these differences on dichotic-listening task performance to establish how characteristics of one's native language affect the perception of nonnative phonological features. We compared 33 native speakers of Norwegian, a language characterized by a clear distinction between voiced and unvoiced initial plosive consonants, with 30 native speakers of Estonian, a language that has exclusively unvoiced initial phonemes. Using a free-report dichotic-listening paradigm utilizing pairs of voiced (/ba/, /da/, /ga/) and unvoiced (/pa/, /ta/, /ka/) stop-consonant vowels as stimulus material, the Norwegian native speakers were found to be more sensitive to the voicing of the initial plosive than the Estonian group. “Voicing” explained 69% and 18% of the variance in the perceptual auditory laterality in the Norwegian and the Estonian sample, respectively. This indicates that experiential differences, likely during acquisition of the mother tongue in early development, permanently shape the sensitivity to the voicing contrast.

The Downside of Greater Lexical Influences: Selectively Poorer Speech Perception in Noise.

Although lexical information influences phoneme perception, the extent to which reliance on lexical information enhances speech processing in challenging listening environments is unclear. We examined the extent to which individual differences in lexical influences on phonemic processing impact speech processing in maskers containing varying degrees of linguistic information (2-talker babble or pink noise). Twenty-nine monolingual English speakers were instructed to ignore the lexical status of spoken syllables (e.g., gift vs. kift) and to only categorize the initial phonemes (/g/ vs. /k/). The same participants then performed speech recognition tasks in the presence of 2-talker babble or pink noise in audio-only and audiovisual conditions. Individuals who demonstrated greater lexical influences on phonemic processing experienced greater speech processing difficulties in 2-talker babble than in pink noise. These selective difficulties were present across audio-only and audiovisual conditions. Individuals with greater reliance on lexical processes during speech perception exhibit impaired speech recognition in listening conditions in which competing talkers introduce audible linguistic interferences. Future studies should examine the locus of lexical influences/interferences on phonemic processing and speech-in-speech processing.