Syllable-based constraints on properties of English sounds

Also issued as Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1989.Includes bibliographical references (p. 169-174).Work sponsored in part by the Office of Naval Research. N00014-82-K-0727Mark A. Randolph

Analyzing and Improving Statistical Language Models for Speech Recognition

In many current speech recognizers, a statistical language model is used to indicate how likely it is that a certain word will be spoken next, given the words recognized so far. How can statistical language models be improved so that more complex speech recognition tasks can be tackled? Since the knowledge of the weaknesses of any theory often makes improving the theory easier, the central idea of this thesis is to analyze the weaknesses of existing statistical language models in order to subsequently improve them. To that end, we formally define a weakness of a statistical language model in terms of the logarithm of the total probability, LTP, a term closely related to the standard perplexity measure used to evaluate statistical language models. We apply our definition of a weakness to a frequently used statistical language model, called a bi-pos model. This results, for example, in a new modeling of unknown words which improves the performance of the model by 14% to 21%. Moreover, one of the identified weaknesses has prompted the development of our generalized N-pos language model, which is also outlined in this thesis. It can incorporate linguistic knowledge even if it extends over many words and this is not feasible in a traditional N-pos model. This leads to a discussion of whatknowledge should be added to statistical language models in general and we give criteria for selecting potentially useful knowledge. These results show the usefulness of both our definition of a weakness and of performing an analysis of weaknesses of statistical language models in general.Comment: 140 pages, postscript, approx 500KB, if problems with delivery, mail to [email protected]

Articulatory and Acoustic Characteristics of German Fricative Clusters

Background: We investigate the articulatory-acoustic relationship in German fricative sequences. We pursue the possibility that /f/#sibilant and /s#integral/ sequences are in principle subject to articulatory overlap in a similar fashion, yet due to independent articulators being involved, there is a significant difference in the acoustic consequences. We also investigate the role of vowel context and stress. Methods: We recorded electropalatographic and acoustic data from 9 native speakers of German. Results: Results are compatible with the hypothesis that the temporal organization of fricative clusters is globally independent of cluster type with differences between clusters appearing mainly in degree. Articulatory overlap may be obscured acoustically by a labiodental constriction, similarly to what has been reported for stops. Conclusion: Our data suggest that similar principles of articulatory coordination underlie German fricative clusters independently of their segmental composition. The general auditory-acoustic patterning of the fricative sequences can be predicted by taking into account that aerodynamic-acoustic consequences of gestural overlap may vary as a function of the articulators involved. We discuss possible sources for differences in degrees of overlap and place our results in the context of previously reported asymmetries among the fricatives in regressive place assimilation. (C) 2016 S. Karger AG, Base

The Status of Coronals in Standard American English . An Optimality-Theoretic Account

Coronals are very special sound segments. There is abundant evidence from various fields of phonetics which clearly establishes coronals as a class of consonants appropriate for phonological analysis. The set of coronals is stable across varieties of English unlike other consonant types, e.g. labials and dorsals, which are subject to a greater or lesser degree of variation. Coronals exhibit stability in inventories crosslinguistically, but they simultaneously display flexibility in alternations, i.e. assimilation, deletion, epenthesis, and dissimilation, when it is required by the contradictory forces of perception and production. The two main, opposing types of alternation that coronals in SAE participate in are examined. These are weakening phenomena, i.e. assimilation and deletion, and strengthening phenomena, i.e. epenthesis and dissimilation. Coronals are notorious for their contradictory behavior, especially in alternations. This type of behavior can be accounted for within a phonetically grounded OT framework that unites both phonetic and phonological aspects of alternations. Various sets of inherently conflicting FAITHFULNESS and MARKEDNESS constraints that are needed for an OT analysis of SAE alternations are intoduced

Individual Differences in Speech Production and Perception

Inter-individual variation in speech is a topic of increasing interest both in human sciences and speech technology. It can yield important insights into biological, cognitive, communicative, and social aspects of language. Written by specialists in psycholinguistics, phonetics, speech development, speech perception and speech technology, this volume presents experimental and modeling studies that provide the reader with a deep understanding of interspeaker variability and its role in speech processing, speech development, and interspeaker interactions. It discusses how theoretical models take into account individual behavior, explains why interspeaker variability enriches speech communication, and summarizes the limitations of the use of speaker information in forensics

Exploring the adaptive structure of the mental lexicon

The mental lexicon is a complex structure organised in terms of phonology, semantics and syntax, among other levels. In this thesis I propose that this structure can be explained in terms of the pressures acting on it: every aspect of the organisation of the lexicon is an adaptation ultimately related to the function of language as a tool for human communication, or to the fact that language has to be learned by subsequent generations of people. A collection of methods, most of which are applied to a Spanish speech corpus, reveal structure at different levels of the lexicon.• The patterns of intra-word distribution of phonological information may be a consequence of pressures for optimal representation of the lexicon in the brain, and of the pressure to facilitate speech segmentation.• An analysis of perceived phonological similarity between words shows that the sharing of different aspects of phonological similarity is related to different functions. Phonological similarity perception sometimes relates to morphology (the stressed final vowel determines verb tense and person) and at other times shows processing biases (similarity in the word initial and final segments is more readily perceived than in word-internal segments).• Another similarity analysis focuses on cooccurrence in speech to create a representation of the lexicon where the position of a word is determined by the words that tend to occur in its close vicinity. Variations of context-based lexical space naturally categorise words syntactically and semantically.• A higher level of lexicon structure is revealed by examining the relationships between the phonological and the cooccurrence similarity spaces. A study in Spanish supports the universality of the small but significant correlation between these two spaces found in English by Shillcock, Kirby, McDonald and Brew (2001). This systematicity across levels of representation adds an extra layer of structure that may help lexical acquisition and recognition. I apply it to a new paradigm to determine the function of parameters of phonological similarity based on their relationships with the syntacticsemantic level. I find that while some aspects of a language's phonology maintain systematicity, others work against it, perhaps responding to the opposed pressure for word identification.This thesis is an exploratory approach to the study of the mental lexicon structure that uses existing and new methodology to deepen our understanding of the relationships between language use and language structure

First Language Attrition: What It Is, What It Isn’t, and What It Can Be

This review aims at clarifying the concept of first language attrition by tracing its limits, identifying its phenomenological and contextual constraints, discussing controversies associated with its definition, and suggesting potential directions for future research. We start by reviewing different definitions of attrition as well as associated inconsistencies. We then discuss the underlying mechanisms of first language attrition and review available evidence supporting different background hypotheses. Finally, we attempt to provide the groundwork to build a unified theoretical framework allowing for generalizable results. To this end, we suggest the deployment of a rigorous neuroscientific approach, in search of neural markers of first language attrition in different linguistic domains, putting forward hypothetical experimental ways to identify attrition’s neural traces and formulating predictions for each of the proposed experimental paradigms

How predictability and givenness produce activation, and acoustic reduction

Speakers tend to use reduced pronunciation, e.g. shorter duration, when words are previously mentioned, or predictable in context. Existing accounts of this phenomenon underspecify whether both giveness and predictability make independent contributions, and say little about the underlying cognitive mechanism. I propose and test the Activation Reduction Hypothesis (ARH), which states that any stimulus that activates representations used for language production should elicit reduced pronunciations. This unites givenness and predictability in a single plausible psychological mechanism, and makes novel predictions, which I tested in three experiments. The first experiment shows that linguistic stimuli elicit more reduction than non-linguistic stimuli, which also elicit reduction. The second shows that linguistic stimuli elicit reduction in the absence of strong predictability, suggesting a role for sheer activation. The third attempts to isolate this reduction at the conceptual level of representation, but shows little supporting evidence

Language and Linguistics in a Complex World Data, Interdisciplinarity, Transfer, and the Next Generation. ICAME41 Extended Book of Abstracts

This is a collection of papers, work-in-progress reports, and other contributions that were part of the ICAME41 digital conference