Lexical Stress Research Articles

Neural correlates of lexical stress processing in a foreign free-stress language.

The paper examines the discrimination of lexical stress contrasts in a foreign language from a neural perspective. The aim of the study was to identify the areas associated with word stress processing (in comparison with vowel processing), when listeners of a fixed-stress language have to process stress in a foreign free-stress language. We asked French-speaking participants to process stress and vowel contrasts in Spanish, a foreign language that the participants did not know. Participants performed a discrimination task on Spanish word pairs differing either with respect to word stress (penultimate or final stressed word) or with respect to the final vowel while functional magnetic resonance imaging data was acquired. Behavioral results showed lower accuracy and longer reaction times for discriminating stress contrasts than vowel contrasts. The contrast Stress>Vowel revealed an increased bilateral activation of regions shown to be associated with stress processing (i.e., supplementary motor area, insula, middle/superior temporal gyrus), as well as a stronger involvement of areas related to more domain-general cognitive control functions (i.e., bilateral inferior frontal gyrus). The contrast Vowel>Stress showed an increased activation in regions typically associated with the default mode network (known for decreasing its activity during attentionally more demanding tasks). When processing Spanish stress contrasts as compared to processing vowel contrasts, native listeners of French activated to a higher degree anterior networks including regions related to cognitive control. They also show a decrease in regions related to the default mode network. These findings, together with the behavioral results, reflect the higher cognitive demand, and therefore, the larger difficulties, for French-speaking listeners during stress processing as compared to vowel processing.

Наголос у структуруванні українського діалектного континууму (дисертація на здобуття наукового ступеня доктора філологічних наук зі спеціальності 10.02.01 – українська мова. Інститут української мови НАН України)

The article views the accent in nouns, adjectives, numerals and pronouns in Ukrainian dialects from the perspective of accent types (fixed / lexical stress). Namely, to some extent the models, the principles of studying and describing the dialectal accent system correlate with the principles, methods of studying the accent system of the literary standard. At the same time, the latter have their own specifics, primarily awareness and researcher orientation in space and time. We need to take into account not only the codified norm but also an area of the dialectal system study, the history of its formation and the age-related characteristics of the speakers.Emphasis Has been placed on the fact that every part of speech has its traits in a grammatical structure, which involves the use of different methods of emphasis. The study analyzes fixed stress placed on the penultimate syllable of a word – a paroxiton, which is definitely opposed to lexical stress. The proposed identified determination of paroxitonic emphasis: fixed stress on the penultimate composition of a word, which may be a constant feature, and paroxitonosis against lexical stress. In the accentuational portraits of Ukrainian zones it was found out that accentuation is an important argument in determining the maternal basis of new-life, transitional and resettlement (island) dialects. The Southwest type of stress is proposed as a territorial literary-normative variant. It is emphasized that this type of akcent is a typical southwestern feature, one of the lingual markers of the region In question.

Perceptual weighting on English lexical stress by Korean learners of English

This study examined which acoustic cue(s) that Korean learners of English give weight to in perceiving English lexical stress. We manipulated segmental and suprasegmental cues in 5 steps in the first and second syllables of an English stress minimal pair “object”. A total of 27 subjects (14 native speakers of English and 13 Korean L2 learners) participated in the English stress judgment task. The results revealed that native Korean listeners used the F0 and intensity cues in identifying English stress and weighted vowel quality most strongly, as native English listeners did. These results indicate that Korean learners’ experience with these cues in L1 prosody can help them attend to these cues in their L2 perception. However, L2 learners’ perceptual attention is not entirely predicted by their linguistic experience with specific acoustic cues in their native language.

Neuronal and behavioral affective perceptions of human and naturalness-reduced emotional prosodies.

Artificial voices are nowadays embedded into our daily lives with latest neural voices approaching human voice consistency (naturalness). Nevertheless, behavioral, and neuronal correlates of the perception of less naturalistic emotional prosodies are still misunderstood. In this study, we explored the acoustic tendencies that define naturalness from human to synthesized voices. Then, we created naturalness-reduced emotional utterances by acoustic editions of human voices. Finally, we used Event-Related Potentials (ERP) to assess the time dynamics of emotional integration when listening to both human and synthesized voices in a healthy adult sample. Additionally, listeners rated their perceptions for valence, arousal, discrete emotions, naturalness, and intelligibility. Synthesized voices were characterized by less lexical stress (i.e., reduced difference between stressed and unstressed syllables within words) as regards duration and median pitch modulations. Besides, spectral content was attenuated toward lower F2 and F3 frequencies and lower intensities for harmonics 1 and 4. Both psychometric and neuronal correlates were sensitive to naturalness reduction. (1) Naturalness and intelligibility ratings dropped with emotional utterances synthetization, (2) Discrete emotion recognition was impaired as naturalness declined, consistent with P200 and Late Positive Potentials (LPP) being less sensitive to emotional differentiation at lower naturalness, and (3) Relative P200 and LPP amplitudes between prosodies were modulated by synthetization. Nevertheless, (4) Valence and arousal perceptions were preserved at lower naturalness, (5) Valence (arousal) ratings correlated negatively (positively) with Higuchi's fractal dimension extracted on neuronal data under all naturalness perturbations, (6) Inter-Trial Phase Coherence (ITPC) and standard deviation measurements revealed high inter-individual heterogeneity for emotion perception that is still preserved as naturalness reduces. Notably, partial between-participant synchrony (low ITPC), along with high amplitude dispersion on ERPs at both early and late stages emphasized miscellaneous emotional responses among subjects. In this study, we highlighted for the first time both behavioral and neuronal basis of emotional perception under acoustic naturalness alterations. Partial dependencies between ecological relevance and emotion understanding outlined the modulation but not the annihilation of emotional integration by synthetization.

System for Automatic Assignment of Lexical Stress in Croatian

It is very popular today to integrate voice interfaces into IoT devices. The pronunciation and proper prosody of speech play a major role in the intelligibility and naturalness of synthesized voices. Each language has its own prosodic characteristics. In this paper, we present the results of a study aimed at testing the applicability of methods for modelling and predicting the prosodic features of the Croatian language. The extent to which their performance can be improved by incorporating linguistic features and linguistic peculiarities specific to the Croatian language was investigated. In the model learning process, tree classification was used to predict the lexical stress position and the type of stress in a word, and a lexicon of 1,011,785 word forms was used as the model learning set. Separate models were created for predicting the position and type of lexical stress. The results improved significantly after the rules for atonic words (clitics) were applied. A hybrid approach combining a rule-based approach and a modelling approach was also proposed. The final accuracy of assigning lexical stress using the hybrid approach was 95.3%.

The Use of Segmental and Suprasegmental Sequencing Skills to Differentiate Children With and Without Childhood Apraxia of Speech: Protocol for a Comparative Accuracy Study.

BackgroundChildhood apraxia of speech (CAS) is a motor-based speech sound disorder (SSD) with a core impairment in the planning and programming of spatiotemporal parameters of speech movement sequences. CAS may cause deficits in both segmental and suprasegmental components of speech, and it can severely affect children’s ability to speak intelligibly and communicate effectively and impact their quality of life. Assessment tasks, such as the maximum performance tasks (MPT) and Syllable Repetition Task (SRT), examine children’s segmental sequencing skills to assist with the diagnosis of CAS. In Hong Kong, although the MPT and SRT have been used clinically to diagnose CAS in Cantonese-speaking children, their validity has not been reported. There is an urgent need for such investigations. Suprasegmentally, lexical stress errors have been reported as a consensual feature and to aid in the diagnosis of CAS. However, there are challenges in diagnosing CAS in children who speak tonal languages like Cantonese. A recent study has reported lexical tone errors in Cantonese-speaking children with CAS. Furthermore, deficits in pitch-variation skills were found in Cantonese-speaking children with CAS using a tone sequencing task (TST). It is hypothesized that there is a universal deficit in pitch-variation skills among tonal and nontonal language speakers with CAS. Further investigations of pitch-variation skills using the TST in Cantonese-speaking children with CAS may shed light on suprasegmental deficits in tonal languages and contribute to the development of a valid diagnostic tool for CAS in children who speak other tonal languages, such as Vietnamese, Thai, and Mandarin.ObjectiveThis study aims to examine the diagnostic potential of the MPT, SRT, and TST in diagnosing Cantonese-speaking children with CAS and to investigate pitch-variation skills in Cantonese-speaking children with and without CAS.MethodsA total of 25 children with CAS and 3 groups of age- and gender-matched controls (non-CAS SSD only group, non-CAS SSD co-occurring with language impairment group, and typical development group) will be recruited. All participants will perform the MPT, SRT, and TST measures. Their performances on these tools will be perceptually judged and acoustically measured.ResultsData collection will last from January 1, 2022, to October 30, 2023. As of August 2022, the project has recruited 4 children in the CAS group, 21 children in the non-CAS SSD group, 4 children in the speech and language impairment group, and 53 children in the typical development group.ConclusionsIt is anticipated that Cantonese-speaking children with CAS will have poorer pitch-variation skills than the control groups and that the MPT, SRT, and TST will be appropriate diagnostic tools for identifying CAS in Cantonese-speaking children. The project will benefit the field of speech-language pathology locally and internationally, with short- and long-term impacts.International Registered Report Identifier (IRRID)DERR1-10.2196/40465

Perceptual training enhances Seoul Korean listeners’ use of vowel quality and pitch cues to English lexical stress

This study investigates whether high-variability (multi-talker) perceptual training is superior to low-variability (single-talker) perceptual training for enhancing Seoul-Korean listeners’ use of vowel quality and pitch cues to English lexical stress. Vowel quality and pitch are the two most important cues to English lexical stress in accented words (Tremblay et al., 2021). Seoul Korean does not have lexical stress, lexical pitch accents, or lexical tones. Seoul-Korean listeners completed a pre-/post-test sequence-recall experiment where they heard and recalled four English words uttered by different talkers. Experimental conditions: The words differed in lexical stress, which was cued by: (i) vowel quality, pitch, and duration; (ii) vowel quality and duration; (iii) pitch and duration; or (iv) duration. Control condition: The words differed in their initial consonant (Seoul-Korean contrast). Listeners completed one of two training types (8 × 30-mins). The words in the training followed a cue distribution that mimicked naturalistic spoken English (Im et al., 2018). Results: Both training types improved listeners’ recall for (i)–(iii), suggesting enhanced use of vowel quality and pitch. Learning gains were greater with high-variability training, but training type did not interact with cue. Thus, high variability provides a global rather than selective enhancement of listeners’ use of cues to lexical stress.

Perception of English lexical stress in different intonational contexts by Mandarin listeners

The present study seeks to elucidate the nature of first language transfer effects on the perception of English lexical stress in different intonational contexts. Pitch (F0) is one of the acoustic cues to lexical stress in English, but crucially, pitch can only serve as a cue to stress when interpreted within the intonation system of English. In contrast, Mandarin is a tonal language where pitch carries greater functional weight for signaling lexical contrasts. Associating pitch to lexical contrasts, Mandarin listeners might therefore assume a one-to-one relationship between pitch and lexical stress in English. To examine whether Mandarin learners of English make this assumption, the current study tested their stress perception in four different intonations: H*L-L%, L*H-H%, H*H-H%, and L*L-L%, where F0 cues to stress were realized differently in each intonation. The results of the stress identification task showed that Mandarin listeners falsely associated higher F0 with stress and lower F0 with the absence of it, and their performance did not improve as they became increasingly proficient in English. The findings provide corroborating evidence for the Cue-Weighting Transfer Hypothesis by showing that the use of a suprasegmental cue can transfer from one phonological category (tones) to another (stress).

Characterization and normalization of second language speech intelligibility through lexical stress, speech rate, rhythm, and pauses

While a range of measures based on speech production, language, and perception are possible (Manun et al., 2020) for the prediction and estimation of speech intelligibility, what constitutes second language (L2) intelligibility remains under-defined. Prosodic and temporal features (i.e., stress, speech rate, rhythm, and pause placement) have been shown to impact listener perception (Kang et al., 2020). Still, their relationship with highly intelligible speech is yet unclear. This study aimed to characterize L2 speech intelligibility. Acoustic analyses, including PRAAT and Python scripts, were conducted on 405 speech samples (30 s) from 102 L2 English speakers with a wide variety of backgrounds, proficiency levels, and intelligibility levels. The results indicate that highly intelligible speakers of English employ between 2 and 4 syllables per second and that higher or lower speeds are less intelligible. Silent pauses between 0.3 and 0.8 s were associated with the highest levels of intelligibility. Rhythm, measured by Δ syllable length of all content syllables, was marginally associated with intelligibility. Finally, lexical stress accuracy did not interfere substantially with intelligibility until less than 70% of the polysyllabic words were incorrect. These findings inform the fields of first and second language research as well as language education and pathology.

The efficacy of lexical stress diacritics on the English comprehensibility and accentedness of Korean speakers

Abstract The purpose of the study was to examine the efficacy of lexical stress diacritics on the English comprehensibility and accentedness of Korean speakers. To this end, 30 native Korean participants read aloud 15 English sentences without diacritics in the pretest. Then, they were given explicit instructions on the production of higher pitch and extended duration as a marker of English stress with musical notation provided. In the posttest, the participants read aloud the same sentences as were in the pretest but which had diacritics indicating stress placement. In the delayed posttest, two days after the pretest and the posttest, the participants read 15 sentences without diacritics again to see if the effects of the treatment were retained. Randomized speech samples were rated by three native speakers of English in relation to comprehensibility and accentedness. Findings showed that significant improvements were observed after the treatment in both comprehensibility and accentedness.

An Investigation of Common Stress Placement Errors in English Word Roots and their Suffixed Derivatives by Arabic-Speaking EFL Learners

Suffixation influences lexical stress in one of three ways. A suffix attached to a word root/stem may take the stress itself, or it may cause it to move from where it was in the uninflected stem to another syllable, or it may keep stress as is. Stress misassignment is very common in the speech of Arabic-speaking English as a foreign language (EFL) learners. This study was conducted to investigate how Arabic-speaking EFL learners at Prince Sattam bin Abdulaziz University (PSAU) in Saudi Arabia assign lexical stress in word roots/stems and their suffixed derivatives to find out whether stress in suffixed words presented a greater challenge to the learners than stress in the stem; the study also aimed to examine whether errors in stress assignment were caused by first language(L1) interference. 112 students from PSAU were randomly chosen to pronounce 80 suffixed words as well as their roots/stems. The pronunciations were recorded, and the recordings were analyzed by the three researchers and three raters. The study concluded that suffixed words do not present a more significant stress assignment challenge than uninflected stems, the type of syllable attached to a word is not as important as the number of syllables, syllable weight and structure in a word, and that L1 influence may be one of the causes but not the only cause of lexical stress misassignment.

Examination of Consonantal Phonetic Coverage in Standard Reading Passages

Purpose: To be effective for clinical and research purposes, materials for eliciting speech should have phonetic coverage of a language, which necessarily includes both phonemic coverage (including all phonemes) and allophonic coverage (including positional contexts). The purpose of this work was to quantify allophonic coverage in widely used standard passages. Method: A total of 466 allowable contexts for 24 consonants in English were determined by taking into account positional contexts in terms of word positions, lexical stress, and proximity to other phonemes. The Caterpillar, The Grandfather Passage , and The Rainbow Passage were analyzed with respect to their phonetic coverage of these allowable contexts. Results: The standard passages achieved phonemic coverage, but their phonetic coverage was minimal: 24.89% in The Caterpillar , 27.25% in The Grandfather Passage , and 35.84% in The Rainbow Passage . Conclusion: Our analysis of three standard passages suggests the need for new speech materials that provide not only phonemic but also allophonic coverage so that production and perception of consonants can be examined as a function of their positional contexts.

RoLEX: The development of an extended Romanian lexical dataset and its evaluation at predicting concurrent lexical information

AbstractIn this article, we introduce an extended, freely available resource for the Romanian language, named RoLEX. The dataset was developed mainly for speech processing applications, yet its applicability extends beyond this domain. RoLEX includes over 330,000 curated entries with information regarding lemma, morphosyntactic description, syllabification, lexical stress and phonemic transcription. The process of selecting the list of word entries and semi-automatically annotating the complete lexical information associated with each of the entries is thoroughly described.The dataset’s inherent knowledge is then evaluated in a task of concurrent prediction of syllabification, lexical stress marking and phonemic transcription. The evaluation looked into several dataset design factors, such as the minimum viable number of entries for correct prediction, the optimisation of the minimum number of required entries through expert selection and the augmentation of the input with morphosyntactic information, as well as the influence of each task in the overall accuracy. The best results were obtained when the orthographic form of the entries was augmented with the complete morphosyntactic tags. A word error rate of 3.08% and a character error rate of 1.08% were obtained this way. We show that using a carefully selected subset of entries for training can result in a similar performance to the performance obtained by a larger set of randomly selected entries (twice as many). In terms of prediction complexity, the lexical stress marking posed most problems and accounts for around 60% of the errors in the predicted sequence.

Spanish heritage speakers’ processing of lexical stress

Abstract This study examines the status of lexical stress in the processing system of heritage speakers of Spanish and whether or not it is influenced by their experience with English. Participants completed an ABX matching task with auditory stimuli differing in the location of stress or in one consonantal sound. Findings reveal that heritage speakers are more accurate in consonant-based trials than in stress-based ones, but only when matching stimuli were non-adjacent, which suggests that their stress-processing strategies pattern more closely with those of native English speakers. Furthermore, dominance and knowledge of Spanish appear to be associated with increased phonological sensibility to stress contrasts. Pedagogical implications are discussed.

Probing effects of lexical prosody on speech-gesture integration in prominence production by Swedish news presenters

This study investigates the multimodal implementation of prosodic-phonological categories, asking whether the accentual fall and the following rise in the Swedish word accents (Accent 1, Accent 2) are varied as a function of accompanying head and eyebrow gestures. Our purpose is to evaluate the hypothesis that prominence production displays a cumulative relation between acoustic and kinematic dimensions of spoken language, especially focusing on the clustering of gestures (head, eyebrows), at the same time asking if lexical-prosodic features would interfere with this cumulative relation. Our materials comprise 12 minutes of speech from Swedish television news presentations. The results reveal a significant trend for larger fo rises when a head movement accompanies the accented word, and even larger when an additional eyebrow movement is present. This trend is observed for accentual rises that encode phrase-level prominence, but not for accentual falls that are primarily related to lexical prosody. Moreover, the trend is manifested differently in different lexical-prosodic categories (Accent 1 versus Accent 2 with one versus two lexical stresses). The study provides novel support for a cumulative-cue hypothesis and the assumption that prominence production is essentially multimodal, well in line with the idea of speech and gesture as an integrated system.

The Acquisition of French Determiners by Bilingual Children: A Prosodic Account

The present longitudinal study investigates the acquisition of determiners (articles) in two simultaneously bilingual French-Italian children aged 1;6,12 until 3;5,17, one of them being French-dominant and the other one being Italian-dominant. Although French and Italian determiners and determiner phrases share some syntactic aspects, they largely differ with respect to noun length and lexical stress in the nominal domain. Prosody is expected to be a decisive factor in the early prosodification of determiners by French-Italian bilinguals. The analysis of more than 4500 noun phrases yields different acquisition paths and cross-linguistic transfer, which can neither be explained by linguistic structure nor by language balance alone. The results are analyzed within the generative framework. The proposed account integrates language-internal and external factors for determiner acquisition in French by bilingual children.

Lexical access in Portuguese stress

Categorical approaches to lexical stress typically assume that words have either regular or irregular stress, and imply that only the latter needs to be stored in the lexicon, while the former can be derived by rule. In this paper, we compare these two groups of words in a lexical decision task in Portuguese to examine whether the dichotomy in question affects lexical retrieval latencies in native speakers, which could indirectly reveal different processing patterns. Our results show no statistically credible effect of stress regularity on reaction times, even when lexical frequency, neighborhood density, and phonotactic probability are taken into consideration. The lack of an effect is consistent with a probabilistic approach to stress, not with a categorical (traditional) approach where syllables are either light or heavy and stress is either regular or irregular. We show that the posterior distribution of credible effect sizes of regularity is almost entirely within the region of practical equivalence, which provides strong evidence that no effect of regularity exists in the lexical decision data modelled. Frequency and phonotactic probability, in contrast, showed statistically credible effects given the experimental data modelled, which is consistent with the literature.

English and Mandarin native speakers’ cue-weighting of lexical stress: Results from MMN and LDN

Past research on how listeners weight stress cues such as pitch, duration and intensity has reported two inconsistent patternss: listeners’ weighting conforms to 1) their native language experience (e.g., language rhythmicity, lexical tone), and 2) a general “iambic-trochaic law” (ITL), favouring innate sound groupings in cue perception. This study aims to tease apart the above effects by investigating the weighting of pitch, duration and intensity cues in stress-timed (Australian English) and non-stress-timed and tonal (Taiwan Mandarin) language speaking adults using a mismatch negativity (MMN) multi-feature paradigm. Results show effects that can be explained by language-specific rhythmic influence, but only partially by the ITL. Moreover, these findings revealed cross-linguistic differences indexed by both MMN and late discriminative negativity (LDN) responses at cue and syllable position levels, and thus call for more sophisticated perspectives for existing cue-weighting models.

Computer-assisted pronunciation training—Speech synthesis is almost all you need

The research community has long studied computer-assisted pronunciation training (CAPT) methods in non-native speech. Researchers focused on studying various model architectures, such as Bayesian networks and deep learning methods, as well as on the analysis of different representations of the speech signal. Despite significant progress in recent years, existing CAPT methods are not able to detect pronunciation errors with high accuracy (only 60% precision at 40%–80% recall). One of the key problems is the low availability of mispronounced speech that is needed for the reliable training of pronunciation error detection models. If we had a generative model that could mimic non-native speech and produce any amount of training data, then the task of detecting pronunciation errors would be much easier. We present three innovative techniques based on phoneme-to-phoneme (P2P), text-to-speech (T2S) and speech-to-speech (S2S) conversion to generate correctly pronounced and mispronounced synthetic speech. We show that these techniques not only improve the accuracy of three machine learning models for detecting pronunciation errors, but also help establish a new state-of-the-art in the field. Earlier studies have used simple speech generation techniques such as P2P conversion, but only as an additional mechanism to improve the accuracy of pronunciation error detection. We, on the other hand, consider speech generation to be the first-class method of detecting pronunciation errors. The effectiveness of these techniques is assessed in the tasks of detecting pronunciation and lexical stress errors. Non-native English speech corpora of German, Italian, and Polish speakers are used in the evaluations. The best proposed S2S technique improves the accuracy of detecting pronunciation errors in AUC metric by 41% from 0.528 to 0.749 compared to the state-of-the-art approach.

Does adding an accent mark hinder lexical access? Evidence from Spanish

Recent research has shown that omitting the accent mark in a Spanish word, which is a language in which these diacritics only indicate lexical stress, does not cause a delay in lexical access (e.g., cárcel [prison] ≈ carcel; cárcel-CÁRCEL ≈ carcel-CÁRCEL). This pattern has been interpreted as accented and nonaccented vowels sharing the abstract letter representations in Spanish. However, adding an accent mark to a nonaccented Spanish word appears to produce a reading cost in masked priming paradigms (e.g., féliz-FELIZ [happy] > feliz-FELIZ). We examined whether adding an accent mark to a non accented Spanish word slows down lexical access in two semantic categorization experiments to solve this puzzle. We added an accent mark either on the stressed syllable (Experiment 1, e.g., cébra for the word cebra [zebra]) or an unstressed syllable (Experiment 2, e.g., cebrá). While effect sizes were small in magnitude, adding an accent mark produced a cost relative to the intact words, especially when the accent mark was added on an unstressed syllable (cebrá > cebra). These findings favor the view that letter identity and (to a lesser extent) accent mark information are encoded during word recognition in Spanish. We also examined the practical implications of these results.