Perceptuo-motor biases in the perceptual organization of the height feature in French vowels

A paraître dans Acta AcusticaInternational audienceThis paper reports on the organization of the perceived vowel space in French. In a previous paper [28], we investigated the implementation of vocal height contrasts along the F1 dimension in French speakers. In this paper, we present results from perceptual identification tests performed by twelve participants who took part in the production experiment reported in the earlier paper. For each subject, stimuli presented in the identification test were synthesized in two different vowel spaces, corresponding to two different vocal tract lengths. The results showed that first, the perceived French vowels belonging to similar height degrees were aligned on stable F1 values, independent of place of articulation and roundedness, as was the case for produced vowels. Second, the produced F1 distances between height degrees correlated with the perceived F1 distances. This suggests that there is a link between perceptual and motor phonemic prototypes in the human brain. The results are discussed using the framework of the Perception for Action Control (PACT) theory, in which speech units are considered to be gestures shaped by perceptual processes

Plasticity in speech production and perception: a study of accent change in young adults.

This thesis presents the results of two studies that investigated how listeners adapt to different regional accents within the same language. Study 1 investigated whether listeners adjusted their vowel categorization decisions when listening to speech produced in different accents of British English. The results demonstrated that some listeners chose different vowels according to the accent of the carrier sentence. The patterns of adjustment were affected by individual differences in language background (i.e., the degree of experience that an individual has had living in multidialectal environments, and whether the individual grew up in the north or south of England), and corresponded to changes in production that speakers make as a result of sociolinguistic factors when living in a multidialectal environment. Study 2 investigated plasticity in speech production and perception among university students, as individuals change their accent from regional to "educated" norms. Subjects were tested before beginning university, 3 months later and on completion of their first year of study. At each stage they were recorded reading a set of test words and a short passage. They also completed two perceptual tasks they found best exemplar locations for vowels embedded in carrier sentences and identified words in noise. The results demonstrated that subjects changed their spoken accent after attending university. The changes were linked to sociolinguistic factors subjects who were highly motivated to fit in with their university community changed their accent more. There was some evidence for a link between production and perception between-subject differences in production and perception were correlated. However, this relationship was weaker for within-subject changes in accent over time

Perception and production of english vowels by brazilian efl speakers

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Letras/Inglês e Literatura Correspondente.This study investigated the relationship between the perception and production of English vowels by 18 highly proficient Brazilian EFL speakers, most of them M.A. and doctoral students of the Graduate Program in English of the Universidade Federal de Santa Catarina. Two experiments were carried out: A production test to measure the first two formants of the learners' English and Brazilian Portuguese (BP) vowels, and an identification test with synthetic stimuli to investigate the L2 (second language) perception of English vowels. The production and perception results reveal that the Euclidean distance between the three English target pairs (/i/-/I/, /E/-/ae/, /U/-/u/) was significantly larger for the American English monolinguals than for the L2 learners, thus indicating that the Brazilians have difficulty in both producing and perceiving these vowels in a native-like fashion. Importantly, some relationship between vowel perception and production was found because the target pairs which were better perceived were also the ones produced more accurately by the L2 learners. These results provide further evidence for the fact that L2 perception outperforms L2 production

Converging toward a common speech code: imitative and perceptuo-motor recalibration processes in speech production

International audienceAuditory and somatosensory systems play a key role in speech motor control. In the act of speaking, segmental speech movements are programmed to reach phonemic sensory goals, which in turn are used to estimate actual sensory feedback in order to further control production. The adult's tendency to automatically imitate a number of acoustic-phonetic characteristics in another speaker's speech however suggests that speech production not only relies on the intended phonemic sensory goals and actual sensory feedback but also on the processing of external speech inputs. These online adaptive changes in speech production, or phonetic convergence effects, are thought to facilitate conversational exchange by contributing to setting a common perceptuo-motor ground between the speaker and the listener. In line with previous studies on phonetic convergence, we here demonstrate, in a non-interactive situation of communication, online unintentional and voluntary imitative changes in relevant acoustic features of acoustic vowel targets (fundamental and first formant frequencies) during speech production and imitation. In addition, perceptuo-motor recalibration processes, or after-effects, occurred not only after vowel production and imitation but also after auditory categorization of the acoustic vowel targets. Altogether, these findings demonstrate adaptive plasticity of phonemic sensory-motor goals and suggest that, apart from sensory-motor knowledge, speech production continuously draws on perceptual learning from the external speech environment

Auditory and speech processing in specific language impairment (SLI) and dyslexia

This thesis investigates auditory and speech processing in Specific Language Impairment (SLI) and dyslexia. One influential theory of SLI and dyslexia postulates that both SLI and dyslexia stem from similar underlying sensory deficit that impacts speech perception and phonological development leading to oral language and literacy deficits. Previous studies, however, have shown that these underlying sensory deficits exist in only a subgroup of language impaired individuals, and the exact nature of these deficits is still largely unknown. The present thesis investigates three aspects of auditory-phonetic interface: 1) The weighting of acoustic cues to phonetic voicing contrast 2) the preattentive and attentive discrimination of speech and non-linguistic stimuli and 3) the formation of auditory memory traces for speech and non-linguistic stimuli in young adults with SLI and dyslexia. This thesis focuses on looking at both individial and group-level data of auditory and speech processing and their relationship with higher-level language measures. The groups of people with SLI and dyslexia who participated were aged between 14 and 25 and their performance was compared to a group of controls matched on chronological age, IQ, gender and handedness. Investigations revealed a complex pattern of behaviour. The results showed that individuals with SLI or dyslexia are not poor at discriminating sounds (whether speech or non-speech). However, in all experiments, there was more variation and more outliers in the SLI group indicating that auditory deficits may occur in a small subgroup of the SLI population. Moreover, investigations of the exact nature of the input-processing deficit revealed that some individuals with SLI have less categorical representations for speech sounds and that they weight the acoustic cues to phonemic identity differently from controls and dyslexics

Cross-language perception and production of English vowels by Portuguese learners: the effects of perceptual training

Doctoral Dissertation in Language Sciences Specialization in English LinguisticsSeveral studies have demonstrated that second/foreign language (L2/FL) speech learning is a challenge to late learners (i.e., adolescents or adults) in terms of perception and production of certain non-native phonemic and phonetic contrasts (Moyer, 2013). The interaction of different factors might explain learners’ difficulties, namely age of onset of learning (AOL), amount of native (L1) and non-native language (NNL) use over time, quantity and quality of NNL input, and the interference from the L1 phonological system (Piske, 2007). The Speech Learning Model (SLM), proposed by Flege (1995), hypothesizes that difficulties in perceiving and, consequently, in producing non-native contrasts are due to the (dis)similarities between the L1 and the NNL phonological systems. The L1 sound system is likely to hinder the formation of new non-native (L2/FL) phonological categories. However, a considerable number of cross-language studies has revealed that phonological learning is attainable for late learners, and their abilities in perceiving and producing segmental and suprasegmental non-native contrasts can improve, since the mechanisms used in the acquisition of the L1 sound system remain intact over the lifespan and can be applied to L2/FL learning (Flege, 1995). Experimental studies that investigated the effects of perceptual training on non-native speech sound perception and production reported its success not only in the modification of adult learners’ perceptual patterns, but also in the improvement of their pronunciation accuracy, confirming, thereby, the plasticity of L2/FL learners’ mature perceptual system (e.g., Aliaga-Garcia, 2013; Pereira & Hazan, 2013; Wang, 2008; Wang et al., 2003). Difficulties in the perception of non-native vowel contrasts have been widely described as a significant part of the problems learners have in L2/FL phonological acquisition/learning (Strange, 2007). Therefore, the present study investigated the effects of perceptual training on the learning of three English contrasts (/i/-/ɪ/; /ɛ/-/æ/; /u/-/ʊ/) by a group of EFL (English as a Foreign Language) learners. This set of vowel contrasts was selected due to reported difficulties European Portuguese native speakers have in perceiving and producing them (Flege, 1994, as cited in Flege, 1995; Rato et al., 2013). The English phonological categories /ɪ/, /æ/ and /ʊ/ tend to be assimilated to the Portuguese vowel sounds /i/, /ɛ/ and /u/, respectively, and no distinction between the two vowels of each pair is made, due to their acoustic and articulatory proximity. Specifically, this study investigated (i) whether a high variability perceptual training, which included stimuli with different phonemic contexts produced by multiple native talkers, had a positive effect on the perception of the English target segments; (ii) if transfer of improvement to oral production was observed; (iii) whether perceptual learning generalized to identification of new words produced by novel talkers; and (iv) if long-term training effects remained. The participants’ perception was assessed three times with an identification test designed with natural stimuli: (1) before the auditory training – pretest; (2) immediately after the training was over – posttest; and (3) two months later – delayed posttest. The perceptual training program consisted of five sessions divided into two blocks, which included discrimination tasks and identification sequences followed by immediate feedback. Production was tested simultaneously in the three phases by means of a sentence-reading task with the target vowel segments. The results show that the Portuguese learners’ performance in the identification of the English vowels improved significantly, and perceptual gains were retained two months after completion of the training sessions. Moreover, the results of the generalization test indicate that there was robust learning of the two front vowel pairs. Acoustic analyses of spoken data revealed that phonological learning transferred to production. In sum, these results support the claim that perceptual learning can occur in a formal non-naturalistic environment within a short period of time and corroborate previous findings on the malleability of L2/FL adult learners’ perceptual systems.Vários estudos têm demonstrado que, na aprendizagem de uma língua não materna (LNM), a perceção e a produção de determinados contrastes fonológicos e fonéticos não nativos são um desafio para aprendentes tardios (adolescentes ou adultos) (Moyer, 2013). Diversos fatores podem explicar essas dificuldades, tais como a idade do início da aprendizagem, a frequência de uso, a quantidade e a qualidade de exposição à LNM e a influência do sistema fonológico da língua materna (L1) (Piske, 2007). O Speech Learning Model (SLM), desenvolvido por Flege (1995), explica que as dificuldades percetivas e, consequentemente, produtivas se devem ao facto de o sistema de sons linguísticos da L1 impedir a formação de novas categorias fonológicas para a segunda língua ou língua estrangeira (L2/LE). No entanto, um número considerável de estudos tem revelado que aprendentes tardios podem aprender a perceber e a produzir contrastes segmentais e suprassegmentais não nativos, uma vez que os mecanismos usados para aprender o sistema de sons da L1 são ativados na aprendizagem de uma LNM e permanecem intactos durante toda a vida (Flege, 1995). Estes estudos empíricos, que investigaram os efeitos do treino percetivo na perceção e produção de sons não nativos, reportaram a sua eficácia não somente na modificação de padrões percetivos, mas também na melhoria da capacidade produtiva dos mesmos, confirmando assim a plasticidade do sistema percetivo dos aprendentes de LNMs (por exemplo, Aliaga- Garcia, 2013; Pereira & Hazan, 2013; Wang, 2008; Wang et al., 2003). Os resultados de extensa investigação indicam que as dificuldades na perceção de contrastes vocálicos não nativos são uma parte significativa dos problemas que os aprendentes revelam na aquisição/aprendizagem fonológica de uma L2/LE (Strange, 2007). Portanto, no presente estudo, investigaram-se os efeitos do treino percetivo na aprendizagem de três contrastes vocálicos da língua inglesa (/i/-/ɪ/; /ɛ/-/æ/; /u/-/ʊ/) por um grupo de aprendentes de inglês como LE. Estes três contrastes foram escolhidos devido às dificuldades percetivas e produtivas que falantes nativos de português europeu revelam na sua aprendizagem (Flege, 1994, citado em Flege, 1995; Rato et al., 2013). As categorias fonológicas /ɪ/, /æ/ e /ʊ/ da L2/LE tendem a ser assimiladas como sons da L1, /i/, /ɛ/ e /u/, respetivamente, não se verificando qualquer distinção entre as vogais dos três contrastes, devido à sua proximidade acústica e articulatória. Especificamente, pretendeu-se (i) observar o efeito de um treino percetivo de alta variabilidade, que incluiu estímulos produzidos por vários locutores nativos em diferentes contextos fonológicos, na melhoria da capacidade percetiva dos segmentos-alvo; (ii) averiguar a transferência da melhoria para a produção oral; (iii) verificar a generalização para novos contextos e novos falantes; e (iv) analisar os efeitos do treino a longo prazo. A perceção dos participantes foi testada três vezes com uma tarefa auditiva de identificação com estímulos naturais: (1) antes do treino – pré-teste; (2) imediatamente depois do treino – pós-teste; e (3) dois meses mais tarde – teste de retenção. O programa de treino consistiu em cinco sessões, divididas em dois blocos, que incluíram tarefas de identificação e de discriminação auditivas seguidas de correção imediata. A produção foi testada, igualmente, em três fases, através da leitura de frases veículo, contendo palavras com os segmentos vocálicos. Os resultados demonstram que os aprendentes portugueses melhoraram significativamente na identificação das vogais-alvo e essa melhoria da sua competência percetiva manteve-se dois meses após o término do treino. Para além disso, os resultados do teste de generalização indicam que houve uma aprendizagem robusta dos dois contrastes vocálicos anteriores. As análises acústicas das produções dos informantes revelaram também uma transferência da aprendizagem para a produção oral. Estes resultados suportam a afirmação de que a aprendizagem ao nível da perceção de fala pode ocorrer em contextos formais, num curto período de tempo, e corroboram resultados anteriores sobre a maleabilidade dos sistemas percetuais fonológicos de aprendentes adultos de uma LNM