Perceptual processing of partially and fully assimilated words in French

International audienceModels of speech perception attribute a different role to contextual information in the processing of assimilated speech. The present study examined perceptual processing of regressive voice assimilation in French. This phonological variation is asymmetric in that assimilation is partial for voiced stops and near-complete for voiceless stops. Two auditory- visual cross-modal form priming experiments were used to examine perceptual compensation for assimilation in French words with voiceless versus voiced stop offsets. The results show that, for the former segments, assimilating context enhances underlying form recovery, whereas it does not for the latter. These results suggest that two sources of information -- contextual information, and bottom-up information from the assimilated forms themselves -- are complementary and both come into play during the processing of fully or partially assimilated word forms

The impact of regional accent variation on monolingual and bilingual infants’ lexical processing

Phonetic variation is inherent in natural speech. It can be lexically relevant, differentiating words, as well as lexically irrelevant indexical variation, which gives information about the talker or context, such as the gender, mood, regional or foreign accent. Efficient communication requires perceivers to discern how lexical versus indexical sources of variation affect the phonetic form of spoken words. While ample evidence is available on how children acquiring a single language handle variability in speech, less is known about how children simultaneously acquiring two languages deal with phonetic variation. This thesis investigates how the bilingual language environment affects children’s ability to accommodate accented speech. We consider three hypotheses. One is that bilingual infants may have an advantage relative to monolinguals due to their greater experience with phonetic variability across their two phonological systems. This is because the lexical representations in bilingual children, who have more experience with accent variation than monolingual children, might be more open to phonetic variation than monolinguals. Representations that are more open to variation might lead to higher flexibility in the word recognition of children with multi-accent input (bilinguals), resulting in accommodation benefits when processing an unfamiliar accent. An alternative hypothesis, however, is that bilingual children may have less stable lexical representations than monolinguals because their vocabulary size in each language is smaller. This could lead to processing costs in accent adaptation, resulting in accommodation disadvantages for bilinguals. The third and final hypothesis is that there would be no difference between bilinguals and their monolingual peers. This is because the effects of greater accent experience but less stable lexical representations in bilinguals may essentially neutralise each other, resulting in equivalent accent accommodation by bilinguals and monolinguals. To evaluate these hypotheses, three experiments were conducted with 17- and 25-month-old bilingual and monolingual children. Their ability to accommodate unfamiliar accented speech was analysed based on their language experience, pre-exposure to the unfamiliar accent, the type of phonetic variation (easy versus difficult phonetic change), and the cognitive demands of the experimental procedure. Taken together, the findings of Experiments 1-3 suggest that bilingual language input neither benefits nor hampers accent adaptation in bilingual children relative to monolingual children. The results carry implications for our current understanding of bilingualism and phonological development

Compensation for complete assimilation in speech perception: The case of Korean labial-to-velar assimilation

In connected speech, phonological assimilation to neighboring words can lead to pronunciation variants (e.g., 'garden bench'→ "gardem bench"). A large body of literature suggests that listeners use the phonetic context to reconstruct the intended word for assimilation types that often lead to incomplete assimilations (e.g., a pronunciation of "garden" that carries cues for both a labial [m] and an alveolar [n]). In the current paper, we show that a similar context effect is observed for an assimilation that is often complete, Korean labial-to-velar place assimilation. In contrast to the context effects for partial assimilations, however, the context effects seem to rely completely on listeners' experience with the assimilation pattern in their native language

The time course of auditory and language-specific mechanisms in compensation for sibilant assimilation

Models of spoken-word recognition differ on whether compensation for assimilation is language-specific or depends on general auditory processing. English and French participants were taught words that began or ended with the sibilants /s/ and /∫/. Both languages exhibit some assimilation in sibilant sequences (e.g., /s/ becomes like [∫] in dress shop and classe chargée), but they differ in the strength and predominance of anticipatory versus carryover assimilation. After training, participants were presented with novel words embedded in sentences, some of which contained an assimilatory context either preceding or following. A continuum of target sounds ranging from [s] to [∫] was spliced into the novel words, representing a range of possible assimilation strengths. Listeners' perceptions were examined using a visual-world eyetracking paradigm in which the listener clicked on pictures matching the novel words. We found two distinct language-general context effects: a contrastive effect when the assimilating context preceded the target, and flattening of the sibilant categorization function (increased ambiguity) when the assimilating context followed. Furthermore, we found that English but not French listeners were able to resolve the ambiguity created by the following assimilatory context, consistent with their greater experience with assimilation in this context. The combination of these mechanisms allows listeners to deal flexibly with variability in speech forms

Cognitive factors in perception and imitation of Thai tones by Mandarin versus Vietnamese speakers

The thesis investigates how native language phonological and phonetic factors affect non-native lexical tone perception and imitation, and how cognitive factors, such as memory load and stimulus variability (talker and vowel context variability), bias listeners to a phonological versus phonetic mode of perception/imitation. Two perceptual experiments and one imitation experiment were conducted with Thai tones as the stimuli and with Mandarin and Vietnamese listeners, who had no experience with Thai (i.e., naive listeners/imitators). The results of the perceptual experiments (Chapters 5 and 6) showed phonological effects as reflected in assimilation types (Categorised vs. UnCategorised assimilation) and phonetic effects indicated by percent choice and goodness ratings in tone assimilation, largely in line with predictions based on the Perceptual Assimilation Model (PAM: Best, 1995). In addition, phonological assimilation types and phonological overlap of the contrasts affected their discrimination in line with predictions based on PAM. The thesis research has revealed the influence of cognitive factors on native language influences in perception and imitation of non-native lexical tones, which contribute differently to different tasks. The findings carry implications for current non-native speech perception theories. The fact that non-native tone imitation deviations can be traced back to native phonological and phonetic influences on perception supports and provides new insights about perception-production links in processing non-native tones. The findings uphold the extrapolation of PAM and ASP principles to non-native tone perception and imitation, indicating that both native language phonological and phonetic influences and their modulation by cognitive factors hold implications for non-native speech perception/learning theories, as well as for second language instruction

The Effects of Sentential Context on the Perception of Assimilated Speech

The aims of this study were to examine the effect of sentential context on perceptual compensation for assimilation and to compare compensation patterns between English and Korean listeners with a high proficiency level in English. To these ends, we conducted two experiments involving English coronal place assimilation. In the discrimination experiment, two types of stimuli (i.e., compound words and sentences) were presented. In the identification experiment, a target token including one of the two types of codas (i.e., coronal and non-coronal consonants) was embedded in a semantically neutral sentence. The results showed that in the discrimination experiment both listener groups demonstrated higher detection rates in sentences rather than in words. However, the Korean listeners were not as sensitive as the English listeners to phonetic differences of coda consonants in the unviable change context, and they showed more variations in detection rates than the English listeners. The results of the identification experiment presented a significant effect of coda type of target tokens on both listener groups. In sum, the L2 advanced learners were able to use sentential context to perceive assimilated speech, as were the L1 listeners.This work was supported by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea (NRF-2017S1A5A2A01027443)

The mental lexicon is fully specified : evidence from eye-tracking

Four visual-world experiments, in which listeners heard spoken words and saw printed words, compared an optimal-perception account with the theory of phonological underspecification. This theory argues that default phonological features are not specified in the mental lexicon, leading to asymmetric lexical matching: Mismatching input ("pin") activates lexical entries with underspecified coronal stops ('tin'), but lexical entries with specified labial stops ('pin') are not activated by mismatching input ("tin"). The eye-tracking data failed to show such a pattern. Although words that were phonologically similar to the spoken target attracted more looks than unrelated distractors, this effect was symmetric in Experiment 1 with minimal pairs ("tin"- "pin") and in Experiments 2 and 3 with words with an onset overlap ("peacock" - "teacake"). Experiment 4 revealed that /t/-initial words were looked at more frequently if the spoken input mismatched only in terms of place than if it mismatched in place and voice, contrary to the assumption that /t/ is unspecified for place and voice. These results show that speech perception uses signal-driven information to the fullest, as predicted by an optimal perception account.peer-reviewe