Infants segment words from songs - an EEG study

Children’s songs are omnipresent and highly attractive stimuli in infants’ input. Previous work suggests that infants process linguistic–phonetic information from simplified sung melodies. The present study investigated whether infants learn words from ecologically valid children’s songs. Testing 40 Dutch-learning 10-month-olds in a familiarization-then-test electroencephalography (EEG) paradigm, this study asked whether infants can segment repeated target words embedded in songs during familiarization and subsequently recognize those words in continuous speech in the test phase. To replicate previous speech work and compare segmentation across modalities, infants participated in both song and speech sessions. Results showed a positive event-related potential (ERP) familiarity effect to the final compared to the first target occurrences during both song and speech familiarization. No evidence was found for word recognition in the test phase following either song or speech. Comparisons across the stimuli of the present and a comparable previous study suggested that acoustic prominence and speech rate may have contributed to the polarity of the ERP familiarity effect and its absence in the test phase. Overall, the present study provides evidence that 10-month-old infants can segment words embedded in songs, and it raises questions about the acoustic and other factors that enable or hinder infant word segmentation from songs and speech

Toward a prenominal syntax? A brief look at statistical alternations

This pilot study aims to show that people indeed use subconscious statistical processing to aid in the acquisition of constructions, and frequent form-function mappings emerge as structures that work well together. The current study is a modified replication of Wells et.al. (2009), in which frequency distributions of NL-English speakers' relative clauses were manipulated, causing them to more quickly process a less frequent, irregular form. The construction under consideration here is the prenominal clause, rare in English, but attested in many primary languages. The hypothesis was that, given minimal exposure to this construction, subjects would statistically re-categorize their linguistic systems. The infrequent/irregular prenominal phrase was compared with the frequent/regular postnominal RC. Pre- and Post-Tests recorded participants’ self-paced reading times. During two brief Experience Blocks, spaced two days apart, subjects received limited exposure to both target structures. Reading times in the prenominal structure decreased more than that of the RC, for each subject, indicating faster processing. A preliminary analysis of results shows that all subjects reanalyzed the statistical distributions of the prenominal clause.Ope

Implicit learning of recursive context-free grammars

Context-free grammars are fundamental for the description of linguistic syntax. However, most artificial grammar learning experiments have explored learning of simpler finite-state grammars, while studies exploring context-free grammars have not assessed awareness and implicitness. This paper explores the implicit learning of context-free grammars employing features of hierarchical organization, recursive embedding and long-distance dependencies. The grammars also featured the distinction between left- and right-branching structures, as well as between centre- and tail-embedding, both distinctions found in natural languages. People acquired unconscious knowledge of relations between grammatical classes even for dependencies over long distances, in ways that went beyond learning simpler relations (e.g. n-grams) between individual words. The structural distinctions drawn from linguistics also proved important as performance was greater for tail-embedding than centre-embedding structures. The results suggest the plausibility of implicit learning of complex context-free structures, which model some features of natural languages. They support the relevance of artificial grammar learning for probing mechanisms of language learning and challenge existing theories and computational models of implicit learning

Perception of phrasal prosody in the acquisition of European Portuguese

A central issue in language acquisition is the segmentation of speech into linguistic units and structures. This thesis examines the role played by phrasal prosody in speech segmentation in the acquisition of European Portuguese, both in the processing of globally ambiguous sentences by 4 and 5 year old children and in early word segmentation by 12 month-old infants. Past studies have shown that phrasal prosody is used by adults in ambiguity resolution, for example to disambiguate syntactically ambiguous sentences involving a low or high attachment interpretation of a given phrase (e.g, Hide the rabbit with a cloth). In a first exploratory experiment, and given previous unclear findings in the literature on European Portuguese, we investigated whether prosodic phrasing might guide speech chunking and interpretation of these globally ambiguous sentences by adult listeners. In an eye-tracking experiment, which also included a pointing task, we found that EP adult speakers were not able to use phrasal prosody to disambiguate the structures tested. Both the results from eye gaze and the pointing task indicated the presence of a high attachment preference in the language, regardless of phrasal prosody. These findings required a better understanding of adult interpretation of these utterances before a productive study could be conducted with young children. Building on the lessons learned from this exploratory study, we conducted two new experiments examining young children (and adults) abilities to use prosody, in a different sort of globally ambiguous utterances where differences in phrasal prosody were triggered by the syntaxprosody interface and part of the common, default prosody of the sentences (i.e., in compound word versus list reading structures, like ‘guarda-chuva e pato,’ umbrella and duck vs. ‘guarda, chuva e pato’, guard, rain and duck). An eye-tracking paradigm (along the lines of De Carvalho, Dautriche, & Christophe, 2016a) was used to monitor the use of phrasal prosody, namely the contrast between a Prosodic Word boundary (PW) in the compound word interpretation and an Intonational Phrase boundary (IP) in the list interpretation, during auditory sentence processing. An offline pointing task was also included. Results have shown a clear developmental trend in the use of phrasal prosody to guide sentence interpretation, from a general inability at age 4 to a still developing ability at age 5, when local prosodic cues were still not enough and the support of distal cues was necessary to achieve disambiguation, unlike for adults. While the previous experiments investigated the ability to use prosody to constrain lexical and syntactic analysis, thus looking into the combination of lexical, syntactic and prosodic knowledge at a young age, in a final set of experiments, we asked whether phrasal prosody is exploited to chunk the speech signal into words by infants, in the absence of prior lexical knowledge. Using a modified version of the visual habituation paradigm (Altvater-Mackensen & Mani, 2013), we tested 12-month-olds use of phrasal prosody in early word segmentation beyond the utterance edge factor, by examining the effects of two prosodic boundaries in utterance internal position, namely the IP boundary (in the absence of pause) and the PW boundary. Our findings showed that early segmentation abilities are constrained by phrasal prosody, since they crucially depended on the location of the target word in the prosodic structure of the utterance. Implications of the findings in this thesis were discussed in the context of prosodic differences across languages, taking advantage of the atypical combination of prosodic properties that characterizes EP.No âmbito da aquisição da linguagem, a segmentação de fala em unidades e estruturas linguísticas é uma questão central. Esta dissertação examina o papel desempenhado pelo fraseamento prosódico na segmentação de fala, na aquisição do Português Europeu (PE), no que diz respeito ao processamento de frases globalmente ambíguas por parte de crianças aos 4 e 5 anos de idade e à segmentação precoce de palavras aos 12 meses. Estudos anteriores mostraram que o fraseamento prosódico é usado pelos adultos na resolução de ambiguidade, por exemplo, para desambiguar frases sintaticamente ambíguas envolvendo uma interpretação de low ou high attachment de um dado sintagma (e.g.,’Hide the rabbit with a cloth’ Esconde o coelho com um pano). Num estudo exploratório, e dados os resultados pouco claros de trabalhos anteriores para o Português Europeu, investigámos se o fraseamento prosódico poderia guiar a organização da fala em unidades específicas, bem como a interpretação das frases globalmente ambíguas, por parte de participantes adultos. Numa experiência de eye-tracking, que incluía também uma tarefa de apontar, observámos que os participantes adultos do PE não conseguiram usar o fraseamento prosódico para desambiguar as estruturas testadas. Quer os resultados do movimento dos olhos quer os da tarefa de apontar evidenciaram a preferência pelo high attachment na língua, independentemente do fraseamento prosódico envolvido. Estes resultados implicaram compreender melhor a interpretação adulta destes enunciados antes de se conduzir um estudo com crianças. Com base nas observações feitas neste estudo exploratório, conduzimos duas experiências novas por forma a examinar a capacidade de uso da prosódia, por parte das crianças (e adultos), num outro conjunto de enunciados globalmente ambíguos, em que as diferenças de fraseamento prosódico foram desencadeadas pela interface sintaxe-prosódia e por parte da prosódia default das frases (i.e., em compostos versus estruturas em formato de lista, como ‘guarda-chuva e pato,’ vs. ‘guarda, chuva e pato’). Um paradigma de eye-tracking (na linha de De Carvalho, Dautriche, & Christophe, 2016a) foi usado para monitorizar o uso do fraseamento prosódico, nomeadamente o contraste entre uma fronteira de Palavra Prosódica (PW) na interpretação de composto e uma fronteira de Sintagma Entoacional (IP) na interpretação de lista, durante o processamento auditivo da frase. Também foi incluída uma tarefa off-line de apontar. Os resultados mostraram um claro desenvolvimento no uso do fraseamento prosódico na interpretação das frases; de uma incapacidade geral de interpretação das frases aos 4 anos a uma clara evolução nas competências aos 5 anos, altura em que as pistas prosódicas locais ainda são insuficientes e o apoio do contexto prosódico da frase é necessário para alcançar a desambiguação, diferentemente do adulto. Enquanto as experiências anteriores investigaram a capacidade de usar a prosódia para restringir a análise lexical e sintática, olhando para a combinação de conhecimento lexical, sintático e prosódico numa idade precoce, num conjunto final de experiências, questionámos se o fraseamento prosódico é explorado, por parte das crianças, para organizar o sinal de fala em palavras, na ausência de conhecimento lexical prévio. Recorrendo a uma versão modificada do paradigma visual habituation (Altvater-Mackensen & Mani, 2013), testámos o uso do fraseamento prosódico para a segmentação precoce de palavras além do fator limite do enunciado, por parte de crianças com 12 meses de idade. Examinámos o efeito de duas fronteiras prosódicas em posição interna de enunciado, nomeadamente a fronteira de IP (na ausência de pausa) e a fronteira de PW. Os nossos resultados mostraram que a capacidade de segmentação precoce é afetada pelo fraseamento prosódico, na medida em que depende da localização da palavra-alvo na estrutura prosódica do enunciado. Partindo da combinação atípica das propriedades prosódicas que caracterizam o PE, as implicações do conjunto de estudos desenvolvidos no âmbito desta dissertação foram discutidas no contexto das diferenças prosódicas entre línguas

The listening talker: A review of human and algorithmic context-induced modifications of speech

International audienceSpeech output technology is finding widespread application, including in scenarios where intelligibility might be compromised - at least for some listeners - by adverse conditions. Unlike most current algorithms, talkers continually adapt their speech patterns as a response to the immediate context of spoken communication, where the type of interlocutor and the environment are the dominant situational factors influencing speech production. Observations of talker behaviour can motivate the design of more robust speech output algorithms. Starting with a listener-oriented categorisation of possible goals for speech modification, this review article summarises the extensive set of behavioural findings related to human speech modification, identifies which factors appear to be beneficial, and goes on to examine previous computational attempts to improve intelligibility in noise. The review concludes by tabulating 46 speech modifications, many of which have yet to be perceptually or algorithmically evaluated. Consequently, the review provides a roadmap for future work in improving the robustness of speech output

Prosodic constraints on statistical strategies in segmenting fluent speech

Learning a spoken language is, in part, an input-driven process. However, the relevant units of speech like words or morphemes are not clearly marked in the speech input. This thesis explores some possible strategies to segment fluent speech. Two main strategies for segmenting fluent speech are considered. The first involves computing the distributional properties of the input stream. Previous research has established that adults and infants can use the transition probabilities (TPs) between syllables to segment speech. Specifically, researchers have found a preference for syllabic sequences which have relatively high average transition probabilities between the constituent syllables. The second strategy relies on the prosodic organization of speech. In particular, larger phrasal constituents of speech are invariably aligned with the boundaries of words. Thus, any sensitivity to the edges of such phrases will serve to place additional constraints on possible words. The main goal of this thesis is to understand how different strategies conspire together to provide a rich set of cues to segment speech. In particular, we explore how prosodic boundaries influence distributional strategies in segmenting fluent speech. The primary methodology employed is behavioral studies with Italian-speaking adults. In the initial experimental chapters, a novel paradigm is described for studying distributional strategies in segmenting artificial, fluent speech streams. This paradigm uses artificial speech containing syllabic noise, defined as the presence of syllables that do not comprise the target nonce words, but occur at random at comparable frequencies. It is shown that the presence of syllabic noise does not affect segmentation. This suggests that statistical computations are robust. We find that, although the presence of the noise syllables do not affect TP computations, the placement of nonce words with respect to each other does. In particular, 'words' with a clumped distribution are better segmented than 'words' with an even spacing. This suggests that even the process of statistical segmentation itself is constrained. The syllabic noise paradigm is utilized to create speech streams as sequences of frames: syllabic sequences of fixed length. 'Words' can be placed at arbitrary positions with respect to these frames; the remaining positions are occupied by noise syllables. By adding pitch and length characteristics of Intonational Phrases (IPs, which are large phrasal constituents) from the native language, the frames can be turned into prosodic 'phrases'. Thus, nonce words can be placed at different positions with respect to such 'phrases'. It is found that 'words' that straddle such 'phrases' are not preferred over non-words, while 'phrase'-internal 'words' are. Removing the prosodic aspects from the frames abrogates this effect. These initial experiments suggest that prosody carves speech streams into smaller constituents. Presumably, participants infer the edges of these 'phrases' as being edges of words, as in natural speech. It is well known that edge positions are salient. This suggests that 'words' at the edges of the 'phrases' should be better recognized than 'words' in the middles. The subsequent experiments show such an edge effect of prosody. The previous results are ambiguous as to the whether prosody blocks the computation of TPs across phrasal boundaries, or acts at a later stage to suppress the outcome of TP computations. It is seen that prosody does not block TP computations: under certain conditions one can find evidence that participants compute TPs for both 'phrase'-medial and phrase'-straddling 'words'. These results suggest that prosody acts as a filter against statistically cohesive 'words' that straddle prosodic boundaries. Based on these results, the prosodic filtering model is proposed. Next, we examine the generality of the prosodic filtering effect. It will be shown that a foreign prosody causes a similar perception of 'phrasal' edges; the edge effect and the filtering effect are both observed even with foreign IPs. Phonologists have proposed that IPs are universally marked by similar acoustic cues. Thus, the results with foreign prosody suggest that these universal cues play a role in the perception of phrases in fluent speech. Such cues include final lengthening and final pitch decline; further experiments show that, at least in the experimental paradigm used in this thesis, pitch decline plays the primary role in the perception of 'phrases'. Finally, we consider the possible bases for the perception of prosodic edges in otherwise fluent speech. It is suggested that this capacity is not purely linguistic, but arises from acoustic perception: we will see that time-reversed IPs, which maintains pitch breaks at 'phrasal' boundaries, can still induce the filtering effect. In an annex, the question of how time-reversed (backward) speech is perceived in neonates is addressed. In a brain imaging (OT) study with neonates, we find evidence that forward speech is processed differently from backward speech, replicating previous results. In conclusion, the task of finding word boundaries in fluent speech is highly constrained. These constraints can be understood as the natural limitations that ensue when multiple cognitive systems interact in solving particular tasks

THE USE OF SEGMENTATION CUES IN SECOND LANGUAGE LEARNERS OF ENGLISH

This dissertation project examined the influence of language typology on the use of segmentation cues by second language (L2) learners of English. Previous research has shown that native English speakers rely more on sentence context and lexical knowledge than segmental (i.e. phonotactics or acoustic-phonetics) or prosodic cues (e.g., word stresss) in native language (L1) segmentation. However, L2 learners may rely more on segmental and prosodic cues to identify word boundaries in L2 speech since it may require high lexical and syntactic proficiency in order to use lexical cues efficiently. The goal of this dissertation was to provide empirical evidence for the Revised Framework for L2 Segmentation (RFL2) which describes the relative importance of different levels of segmentation cues. Four experiments were carried out to test the hypotheses made by RFL2. Participants consisted of four language groups including native English speakers and L2 learners of English with Mandarin, Korean, or Spanish L1s. Experiment 1 compared the use of stress cues and lexical knowledge while Experiment 2 compared the use of phonotactic cues and lexical knowledge. Experiment 3 compared the use of phonotactic cues and semantic cues while Experiment 4 compared the use of stress cues and sentence context. Results showed that L2 learners rely more on segmental cues than lexical knowledge or semantic cues. L2 learners showed cue interaction in both lexical and sublexical levels whereas native speakers appeared to use the cues independently. In general, L2 learners appeared to have acquired sensitivity to the segmentation cues used in L2, although they still showed difficulty with specific aspects in each cue based on L1 characteristics. The results provided partial support for RFL2 in which L2 learners' use of sublexical cues was influenced by L1 typology. The current dissertation has important pedagogical implication as findings may help identify cues that can facilitate L2 speech segmentation and comprehension

Simultaneous Speech Segmentation and Cross-Situational Statistical Learning in Monolinguals, Bilinguals, and Multilinguals

Statistical learning (SL) is a mechanism that learners use to segment words from continuous speech and map them to their correct referents through the computation of co-occurrence probabilities (Saffran et al., 1996a,1996b; Yu & Smith, 2007). So far, most SL studies have investigated segmentation and mapping using separate tasks (Graf-Estes et al., 2007). Therefore, very little is known about how these two processes interact, which is crucial to understand real world language learning. Moreover, nothing is known about how knowledge of an additional language influences this interaction. In this study, we exposed monolinguals, bilinguals, trilinguals, and quadrilinguals to a joint SL task allowing the tracking of both syllable co-occurrences and word-object co-occurrences at the same time. Two familiarization phases were used, during which participants simultaneously heard two phrases of an artificial language and saw two unique objects on the screen across multiple trials. In the test phase, participants were tested on their speech segmentation and mapping abilities. Our results indicated that although all groups showed different learning trajectories and strategies, they all succeeded at learning label words and mapping them to their correct referents after a second exposure. We also found that quadrilinguals outperformed both bilinguals and monolinguals in segmenting label words. Our preliminary findings suggest that, regardless of language experience, learners are capable of overcoming the cognitive load and the complexity of computing simultaneously available segmentation and mapping statistics, provided they are given sufficient exposure. In addition, knowledge of four languages could enhance the ability to detect word boundaries using statistical information